Comment 9 for bug 1913570

François, this is a different (although related) issue: this bug report was about firefox not even opening a file selection dialog to pick a certificate file, which was resolved after installing xdg-desktop-portal. The problem you're describing is that after selecting the certificate file, firefox fails to actually import it. I can observe the same problem, so that's definitely a bug. Would you mind filing an upstream bug at https://bugzilla.mozilla.org/enter_bug.cgi#h=dupes|Firefox to track the problem, making sure to include "snap" in the bug title, and marking it as blocking https://bugzilla.mozilla.org/show_bug.cgi?id=1665641 ?

Thanks in advance!