Rare behaviour

Hi, Gang!!!

I use MuseScore 3.4.2 Portable AppImage in a computer with Ubuntu Studio (64 bits Linux).

Since a while, I've noted a very rare behaviour... Each time I want to insert one or more bars in any middle part of any score..., Musescore is inmediatelly end and out to the system.

I don't lose any, because, when I start Musecore again, the program gives me the capability to get back to the last work, without lost things.

I can insert bars at the start and at the end of any score, but not in the middle.

Is this a known bug? Is it something only in my system? Do somebody know some way to fix this? ???

Blessings and greetings from Chile!!!

JUAN