Boot Camp: Could not locate the macOS volume

Hello!

A while ago I purchased 21'5 iMac (Mid 2017), it came with macOS High Sierra. The setup was pretty easy, but after some time I understood that sometimes I need Windows specific applications, so I have followed the guide and installed Windows 10 (April Update 2018) throw Boot Camp utility. It is a great experience, because Windows 10 was and is working so fast and fluid on this iMac like it never did or does even on my high-end PC's.

About a week ago App Store asked if I want to upgrade to Mojave, the update process wasn't fast, but it's ok. After that on 01/10/2018 I have restarted iMac from macOS to Windows 10 and it automatically installed two updates while I was working (nothing else was installed):

1. Definition Update for Windows Defender Antivirus - KB2267602,
2. Intel Corporation - Display - 2/28/2018 12:00:00 AM - 23.20.16.4973.

I wanted to restart Windows 10 back to macOS, but the Boot Camp failed with error message: "Could not locate the macOS volume", Boot Camp Control Panel doesn't show macOS, while macOS Startup Disk correctly shows Windows and macOS systems (see pictures below).

I searched for options to start the iMac with macOS and found out about the Option key and it wasn't so hard to do, but now:

• When iMac starts, it is loading Windows 10, so I need to hold the key or wait until the boot is complete and restart again to start macOS;
• Even when I'm turning machine off, while on macOS it will always start with Windows on next launch.

I have three questions:

• Which of the OS updates could cause this strange Boot Camp behaviour: macOS Mojave upgrade or Windows Update's Display driver's update? Maybe uninstall or downgrade will rollback this changes and Boot Camp will work as before?
• If the problem with Boot Camp cannot be solved (or if it requires Windows reinstallation), is there a way to configure iMac to always load macOS first and only then from the macOS restart to Windows?
• Is there a way to automate restart from OS to OS process, e.g. create a shortcut to a cmdlet or macOS terminal command?

P.S. DiskPart on Windows 10 says that the type of macOS partition is unknown: is it expected?

Microsoft DiskPart version 10.0.17134.1 Copyright (C) Microsoft Corporation. On computer: DESKTOP-82SL41M DISKPART> select disk 0 Disk 0 is now the selected disk. DISKPART> list partition Partition ### Type Size Offset ------------- ---------------- ------- ------- Partition 1 System 200 MB 20 KB Partition 2 Unknown 836 GB 200 MB Partition 3 Primary 94 GB 836 GB DISKPART> list volume Volume ### Ltr Label Fs Type Size Status Info ---------- --- ----------- ----- ---------- ------- --------- -------- Volume 0 C BOOTCAMP NTFS Partition 94 GB Healthy Boot Volume 1 EFI FAT32 Partition 200 MB Healthy System

Thank you for your patience for reading such long and full of mistakes text and for your help!