Version 115? Does it reproduce after Help > Troubleshoot Mode?

Thanks for the reply, Wayne. Version 115.2.2 I tried troubleshooting mode, and still had the same problem.

When you say you have a message "open", do you mean open in its own window?

When you say "I have to close that email and delete or junk it from the Inbox." do you mean from the message list?

Check tools > developer > error console immediately after a failed action.

When I say "open", I just mean that I have clicked the email in my inbox so that I can read it.

When I click "delete" or "junk", it's when I have that email open to read. I can delete or junk emails fine when I'm just looking at the Inbox list.

I've attached a screenshot of the error concole.

Hi, Wayne. Have you given up on trying to identify and/or fix this bug?

Please expand the contents of one of those errors - click on the sideways "arrow" a the left

Is this what you need?

Hi, Wayne. I finally identified the source of the problem: there was an incompatibility between Thunderbird and the driver for my LogiTech keyboard/mouse. I just got a new LogiTech keyboard and mouse, and the problem went away. Just thought you'd like to know. I had absolutely no problems with the old keyboard/mouse, other than with Thunderbird.

False alarm, Wayne. The new keyboard/mouse and driver fixed the problem for about a week, but now it's back. I tried deleting all of my .msf files, and completely deleted my Trash and Junk folders, and I reinstalled Thunderbird, but the problem persists. Very frustrating. Any ideas?

You are looking at this as a Thunderbird problem, but I strongly suspect you're having problems with your mouse and keyboard driver/software and/or settings and you should approach it as a mouse/keyboard problem if you want a proper solution. Is it a combo unit, that is, both mouse and keyboard use the same wireless dongle? There are multiple reports of similar problems here https://www.google.com/search?q=logitech+mouse+keyboard+bug