Hey there sugscott,
We'd like to help get you back to organizing files on your Mac without any issues.
As you already have macOS 11.2.3 installed, we can rule out being outdated as a possible cause. Let's continue ruling out some other possible causes:
- A full or nearly full storage could cause this type of thing to occur. How much available built-in storage do you have? You can find out by clicking on the Apple logo at the top left corner of the screen, then on About This Mac > Storage.
- What happens exactly when you try deleting a file to put in the Trash? The more details we have, the better equipped we'll be to help.
- If you haven't tried one yet, we recommend a restart. Check out the section 'Restart' here: Log out, sleep, wake, restart, or shut down your Mac
We look forward to hearing about these details, and take care!