It used to work but haven't tried using it in at least six months. The way I used to use it was to hit the backslash key \ followed by a character code followed by a space. An example of a character code would be ^2, which would give me a superscript 2. This matches what I see in UnicodeMath's README.
Now, nothing happens - the backslash and whatever else I typed after it appear as plain text in my document. I have tried this in a .txt file, a .py file, and a .c file (does that matter to this plugin?). This is in Ubuntu 22.04.
According to my Preferences, Package Settings menu, the package is installed.
RemoveLineBreaks is one I installed recently, and it works. I just removed some syntax highlighting packages in case they were interfering (and I closed SublimeText and opened it again). I tried uninstalling RemoveLineBreaks and that didn't help. I tried uninstalling and reinstalling UnicodeMath. Package Control says there are no disabled packages to enable.
Any ideas? Thank you.