I see, @nbianca do you remember looking at this. I recall we used to delay the edit till we pulled the latest “raw” for the post.
I think it is correct to always protect against missing message bus messages.
Technically this looks a bit like a message bus glitch. I added some code in the past that is meant to recover and switch back to long polling when you reactivate an old tab, but maybe it is missing this particular usage case.