MuseScore 3.5 on Linux - export window not changing file extension

Hi!
I'm using MuseScore 3.5 on latest version of Linux Mint (64-bit, Appimage).
Today I've tried to export my score as midi file, what I did was:
File > Export > in export window I've chose "Standard midi file", but default name of file was score_name.pdf, so I've changed it to score_name.midi and clicked "save". There was no error message, my file was not created.

So I thought that it is some kind of bug in MS 3.5. I've opened my score in MuseScore 3.4.2 and successfully exported midi file. In MuseScore 3.4.2 export window is automaticly changing file extension to .mid, in 3.5 setting file type has no effect on file extension.

My bad - I was trying to export .midi instead .mid. When i type file name as score_name.mid, it exports just fine.

But export window should change file extension when user is changing file type.