Message window self-closing
With Thunderbird 78.4.0, 32-bit, I will be reading msgs. in an open window. Stepping through them using "F" and all of a sudden, the window will close when trying to go to the next msg. It may be on the first advance or the fifth...or any other. It doesn't happen all the time, maybe half a dozen times a week.
I use Thunderbird on two Win 10, 64-bit machines 1500 miles apart so it can't be the computer, ISP or any other common component.
Has this been experienced by anyone else and/or is it being addressed?