I am having the same issue. Space bar doesn't work when I am typing, whether it is in a text or a heading. I can type a whole sentence and zero spaces show up between words. If I go back and put the cursor in between words and then hit the space bar, it works, but not while typing regularly. I can copy and paste text from a word document and it keeps the spaces, but then I have to go and change all the formatting every time once it's in the email body. Not really a solution. I also tried Firefox in troubleshooting mode, no add-ons, and private mode. None of them worked. I'm running the latest version of firefox (99.0.1, 64-bit) on Windows 10 Pro.
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