Thunderbird composition window ignores space bar
I've been using Thunderbird for email since forever. Mostly, I've been on a PC without issues, but once, a number of years ago, I had an old white MacBook (ca. 2010), and thunderbird always worked well on that. But, I recently got a 14" MacBook Pro (OS 12.4), and I'm having terrible problems. When I try to compose an email message the space bar won't work, literally. It will not allow me to space between words. I have a sort of work around in that if I do opt+space or shift+space, I can insert a space. But I've been touch typing for more than 60 years, so this is not a good option.
What I've been doing is composing my messages in text edit, then copying and pasting into TB, but that's a rather stupid approach. I have also had intermittent problems with the spacing issue in MS Word, and, I believe, EverNote.
I'm guessing something is defective in my shiny new MacBook. Anyone have any ideas?
MacBook Pro Apple Silicon