File Transfer doesn't work with my phone anymore

I used to be able to connect to my PC from my phone and copy files back and forth at will. Now this no longer works. On the Android app, I navigate to the files on either my phone or my remote PC (doesn't matter which) and select them fine. When I switch to the opposite device and tap the Perform Action menu to select Copy Here, that option no longer exists. I can view and select files but I can't do any copying at all. Why did this happen out of the blue?

Also tried TeamViewer Host and Quick Session apps on my Android phone and tried to connect from my PC but the PC app does not offer the option of File Transfer anywhere. The Android apps do have permission to access Files. It just simply won't offer the option in the app on Android or PC. I can't find anyone else having this issue. Am I the only one? What's going on??