Desktop and Finder folders don't update right away when items are added/moved.
I changed my video card recently, which might be part of the problem. If I drag a file to the desktop, it sometimes takes over a minute to show up. If I open a jpeg for editing from a finder window in icon mode, then edit and save it, the icon doesn't change until minutes later. If I save attachments from apple mail to the desktop, they don't show up right away. If I open several image files from a Finder window in icon mode, and delete some of them in Preview, when I close Preview the icons for the deleted files still show in the Finder window. If I open one of the "deleted" files it is actually an image file from farther down the list in the Finder window. It seems like changes to Finder windows don't update right away. I was using an Nvidia graphics card until Apple recently killed the drivers, I haven't had any other issues with my setup.
MacPro (early 2009 with processor upgrades)
MacOS 10.13.6 High Sierra (17G14042)
Radeon RX 560x4GB
2x3.06 GHz 6-core Xeon
64 GB DDR3
1TB SSD main drive, APFS
Mac Pro, macOS 10.13