Are you using the Gutenberg block editor? That editor can cause an irregular problem with auto-Tweeting, but I haven’t been able to isolate it. I can usually replicate it once or twice, then it will suddenly start working again, which doesn’t give me enough of a window to identify why it didn’t work.
It’s there but I perfer to use the classic code editor.
Do you mean that you’re using the classic editor plug-in? If so, that shouldn’t be a problem; the changes in Gutenberg don’t effect WP to Twitter if you’re using the classic editor plug-in.
I am using the classic editor plugin and I’m afraid it is still not working.
If you’d like to submit a support request, I’m happy to try and help work out what the problem is; but let me know.