Export frame - bug - no export neither no any message

What is your operating system?
Ubuntu 18.04

What is your Shotcut version (see Help > About Shotcut)? Is it 32-bit?

Can you repeat the problem? If so, what are the steps?
(Please be specific and use the names as seen in Shotcut, preferably English. Include a screenshot or screen recording if you can. Also, you can attach logs from either View > Application Log or right-click a job and choose View Log.)
It’s repeatable. I want to export one frame as png image. I enter export frame menu. Next instead of accepting default file name i put ex. blabla BUT WITHOUT any extension (I replace default file name). Png is selected as type of file. And then after clicking save, nothing saves. There is no any warning message. If I change the name from blabla to blabla.png then saving frame works ok. Definitely it’s some kind of problem with missing file extension. In my opinion in such a situation shotcut should either automatically add png extension (as png is selected as file type), either should display any error message. Just ignoring saving is the worst option here.

I just tried it with version 21.10.31 and it works as expected. The PNG file is saved.

I think this happens on Linux because Shotcut is relying upon the file save dialog to add an extension based on the file types value, which it does on Mac and Windows.

Yeah it might be the reason. Any possibility to add any workaround?

Yes, accepting to come back to it.

I am not able to reproduce this, and I found code already in place to handle this situation with last changes in this area in the 21.05 version.

Should I prepare a short video presenting this mini bug?