Hello Luis Sequeira1,
Also thank you for your time! I checked the extended attributes and but I couldn't find anything suspicious here's an example

All desktop file seem to have the hidden flag, so I removed the hidden flag with your command, but I am very sure it will be hidden after a reboot.
I created a new file and booted up in safe mode. And it was like you said, the file wasn't hidden, but after I booted it without safe mode it hid again. But thanks to you and ChrispyT I am understanding the problem more and more.
Here is the Etrecheck output, but I couldn't find anything suspicious again.
EtreCheck version: 3.4 (420)
Report generated 2017-06-10 23:48:15
Download EtreCheck from https://etrecheck.com
Runtime: 2:17
Performance: Excellent
Click the [Lookup] links for more information from Apple Support Communities.
Click the [Details] links for more information about that line.
Click the [Clean up] link to delete unused files.
Problem: Other problem
Hardware Information: ⓘ
MacBook Pro (15-inch, 2016)
[Technical Specifications] - [User Guide] - [Warranty & Service]
MacBook Pro - model: MacBookPro13,3
1 2,6 GHz Intel Core i7 (i7-6700HQ) CPU: 4-core
16 GB RAM Not upgradeable
BANK 0/DIMM0
8 GB LPDDR3 2133 MHz ok
BANK 1/DIMM0
8 GB LPDDR3 2133 MHz ok
Bluetooth: Good - Handoff/Airdrop2 supported
Wireless: en0: 802.11 a/b/g/n/ac
Battery: Health = Normal - Cycle count = 182
iCloud Quota: 4.74 GB available
Video Information: ⓘ
Intel HD Graphics 530 - VRAM: 1536 MB
Color LCD 3360 x 2100
AMD Radeon Pro 450 - VRAM: 2048 MB
Disk Information: ⓘ
Disk Information: ⓘ
APPLE SSD SM0256L disk0: (251 GB) (Solid State - TRIM: Yes)
(disk0s1) <not mounted> [EFI]: 315 MB
(disk0s2) <not mounted> [CoreStorage Container]: 161.36 GB
Recovery HD (disk0s3 - Journaled HFS+) <not mounted> [Recovery]: 650 MB
BOOTCAMP (disk0s4 - NTFS) /Volumes/BOOTCAMP : 80.68 GB (17.28 GB free)
USB Information: ⓘ
USB30Bus
Apple Inc. iBridge
USB31Bus
USB31Bus
Thunderbolt Information: ⓘ
Apple Inc. thunderbolt_bus_1
Apple Inc. thunderbolt_bus_0
Virtual disks: ⓘ
Macintosh HD (disk1 - Journaled HFS+) / [Startup]: 161.00 GB (23.33 GB free)
Physical disk: disk0s2 161.36 GB Online
System Software: ⓘ
macOS Sierra 10.12.5 (16F73) - Time since boot: less than an hour
Configuration files: ⓘ
/etc/hosts - Count: 2
Gatekeeper: ⓘ
Mac App Store and identified developers
Clean up: ⓘ
/Library/LaunchAgents/com.cisco.anyconnect.gui.plist
open --wait-apps /Applications/Cisco/Cisco AnyConnect Secure Mobility Client.app
Executable not found!
One orphan file found. [Clean up]
Kernel Extensions: ⓘ
/Applications/MATLAB_R2016b.app
[not loaded] com.mathworks.sldrtkrn (5.3.0 - OS X 10.8) [Lookup]
/Applications/Parallels Access.app
[loaded] com.parallels.virtualhid (1.0.3 - SDK 10.9) [Lookup]
[loaded] com.parallels.virtualsound (1.0.36 - SDK 10.6) [Lookup]
/Applications/Parallels Desktop.app
[not loaded] com.parallels.kext.hypervisor (12.2.0 415** - SDK 10.9) [Lookup]
[not loaded] com.parallels.kext.netbridge (12.2.0 415** - SDK 10.9) [Lookup]
[not loaded] com.parallels.kext.usbconnect (12.2.0 415** - SDK 10.9) [Lookup]
[not loaded] com.parallels.kext.vnic (12.2.0 415** - SDK 10.9) [Lookup]
/Library/Application Support/VirtualBox
[loaded] org.virtualbox.kext.VBoxDrv (5.1.14) [Lookup]
[loaded] org.virtualbox.kext.VBoxNetAdp (5.1.14) [Lookup]
[loaded] org.virtualbox.kext.VBoxNetFlt (5.1.14) [Lookup]
[loaded] org.virtualbox.kext.VBoxUSB (5.1.14) [Lookup]
System Launch Agents: ⓘ
[not loaded] 6 Apple tasks
[loaded] 178 Apple tasks
[running] 98 Apple tasks
System Launch Daemons: ⓘ
[not loaded] 43 Apple tasks
[loaded] 167 Apple tasks
[running] 107 Apple tasks
Launch Agents: ⓘ
[loaded] com.cisco.anyconnect.gui.plist (? 40bd3462 0 - installed 2015-10-23) [Lookup] - --wait-apps: Executable not found!
[loaded] com.oracle.java.Java-Updater.plist (? db056c14 be93c7fb - installed 2017-01-21) [Lookup]
[loaded] com.parallels.mobile.prl_deskctl_agent.launchagent.plist (Parallels, Inc. - installed 2017-01-21) [Lookup]
Launch Daemons: ⓘ
[running] com.cisco.anyconnect.vpnagentd.plist (? a7cbca7 3c67d750 - installed 2015-10-23) [Lookup]
[running] com.docker.vmnetd.plist (Docker Inc - installed 2017-04-09) [Lookup]
[loaded] com.microsoft.autoupdate.helper.plist (Microsoft Corporation - installed 2017-04-13) [Lookup]
[loaded] com.microsoft.office.licensingV2.helper.plist (Microsoft Corporation - installed 2016-04-11) [Lookup]
[loaded] com.oracle.java.Helper-Tool.plist (Shell Script e3fefdd2 - installed 2017-01-11) [Lookup]
[running] com.parallels.mobile.dispatcher.launchdaemon.plist (Parallels, Inc. - installed 2017-01-21) [Lookup]
[loaded] com.parallels.mobile.kextloader.launchdaemon.plist (Apple, Inc. - installed 2017-04-29)
[not loaded] org.eyebeam.SelfControl.plist (Charlie Stigler - installed 2017-01-17) [Lookup]
[not loaded] org.virtualbox.startup.plist (Shell Script 700b9385 - installed 2017-03-02) [Lookup]
User Launch Agents: ⓘ
[loaded] com.dropbox.DropboxMacUpdate.agent.plist (Dropbox, Inc. - installed 2017-05-31) [Lookup]
[loaded] com.google.keystone.agent.plist (Google, Inc. - installed 2017-03-29) [Lookup]
[loaded] com.parallels.mobile.startgui.launchagent.plist (Parallels, Inc. - installed 2017-03-02) [Lookup]
[loaded] com.skype.skype.shareagent.plist (Skype Communications S.a.r.l - installed 2017-06-10) [Lookup]
[running] com.spotify.webhelper.plist (Spotify - installed 2017-06-10) [Lookup]
[not loaded] org.virtualbox.vboxwebsrv.plist (Oracle America, Inc. - installed 2017-03-02) [Lookup]
User Login Items: ⓘ
Parallels Toolbox Application
(/Applications/Parallels Toolbox.app)
Spotify Application - Hidden
(/Applications/Spotify.app)
Dropbox Application
(/Applications/Dropbox.app)
Cisco AnyConnect Secure Mobility Client Application - Hidden
(/Applications/Cisco/Cisco AnyConnect Secure Mobility Client.app)
Internet Plug-ins: ⓘ
QuickTime Plugin: 7.7.3 (installed 2017-05-24)
JavaAppletPlugin: Java 8 Update 121 build 13 (installed 2017-01-21) Check version
Safari Extensions: ⓘ
[enabled] Open in Internet Explorer - Parallels - http://www.parallels.com (installed 2017-04-05)
3rd Party Preference Panes: ⓘ
Java (installed 2017-01-21) [Lookup]
Time Machine: ⓘ
Time Machine not configured!
Top Processes by CPU: ⓘ
16% Mail
9% WindowServer
9% com.apple.WebKit.WebContent
6% kernel_task
5% Safari
Top Processes by Memory: ⓘ
1015 MB kernel_task
564 MB com.apple.WebKit.WebContent
219 MB Spotify Helper
181 MB Dropbox
177 MB WindowServer
Top Processes by Network Use: ⓘ
Input Output Process name
8 MB 1 MB com.apple.WebKit.Networking
120 KB 60 KB Spotify
68 KB 107 KB Dropbox
104 KB 38 KB Mail
17 KB 118 KB biometrickitd
Top Processes by Energy Use: ⓘ
3.50 WindowServer
2.94 iTerm2
2.68 com.apple.WebKit.WebContent
2.02 com.docker.hyperkit
Virtual Memory Information: ⓘ
10.20 GB Available RAM
6.77 GB Free RAM
5.80 GB Used RAM
3.44 GB Cached files
0 B Swap Used
Software installs: ⓘ
Microsoft Office 2016 for Mac: (installed 2017-05-19)
Knuddels: (installed 2017-06-02)
Install information may not be complete.
Diagnostics Information: ⓘ
2017-06-09 20:11:57 storedownloadd High CPU use [Open] [Details]
2017-06-09 09:04:53 Microsoft Word.app High CPU use [Open] [Details]
But now I am going to rest and continue tomorrow, it's very late here in Germany. Have a nice day
Thank you for the time & help!