Cannot Delete Photos and No Recently Deleted Folder

Hello, mKIa.

It sounds like your computer has become confused.

Reboot your computer and see if the problem goes away.

If that doesn't fix the issue, see if the problem still happens in Safe mode (hold the shift key down at startup)

How to use safe mode on your Mac - Apple Support 

Does the problem persist while in Safe mode? 

Exit safe mode by restarting your Mac normally and re-evaluate the issue again after a normal reboot

mKla wrote:

The Photos App (version 5.0) on my iMac (2012 running Catalina) will not let me delete photos. It goes through all the motions of a delete, the confirmation pop-up, the activity bar letting me know when the selected photos are deleted, and then nothing: the pictures remain in the spot where they were. I attempt this from 'Photos' view, the 'Photo Stream', but no luck. I'm not using the Cloud for photos.

Also, my sidebar has no 'Recently Deleted' folder. Isn't it supposed to have one?

Is this just the beginning of the end for this software because of my computer's age?

If a Safe Boot does not straighten out on reboot—

Since there is no stand-alone Photo.app to reinstall You can re-install the macOS on top of the macOS for a refreshed copy. User data remains.

How to reinstall macOS from macOS Recovery - https://support.apple.com/en-us/HT204904