On 23 Jul 2020, at 22:41, Charles R. Siegel wrote:

Very weird. It didn't work yesterday, but I just tried it again before I saw this email and now it is working. When I tried it yesterday, it would change the name of the file in TextMate to a some type of temporary file name and the file wouldn't update. But it seems to be working properly now.

That the name was changed to a temporary name seems to indicate that nvALT moved the original file that was being edited with TextMate, and then wrote a new file in the old location.

Which version of TextMate are you using? And can you clarify how you “modify the file (being open) with nvALT” (so that I can try to reproduce)?