I can confirm the last comment by ads. It's good to see progress. Unfortunately, there are still some corner cases where this fails and thus I am reopening.
The case I was still able to reproduce is when the file name has already been preselected. Firefox will warn if you want to overwrite the "file" which is actually a directory. Even if confirming to overwrite, the printing then still simply silently fails.
I can confirm the last comment by ads. It's good to see progress. Unfortunately, there are still some corner cases where this fails and thus I am reopening.
The case I was still able to reproduce is when the file name has already been preselected. Firefox will warn if you want to overwrite the "file" which is actually a directory. Even if confirming to overwrite, the printing then still simply silently fails.