AppImage crash with LV2 GUI efects

This only happens in the appImage, not in the compiled version.
It doesn't happen every time, but it is frequent.
Interestingly, it doesn't happen with Calf Suite, but it does with most plugin GUIs, apparently only LV2.

Steps to reproduce:

1. Load a synthesizer on a MIDI track.

2. Load an LV2 effect plugin with a GUI afterward (LSP, GX (Guitarrix, etc.).

When you close the effect's GUI, sometimes Qtractor crashes.

This doesn't happen if:

1. The effect isn't receiving audio.

2. If you turn off the effect before closing the GUI, close it, and then active it.

It's frustrating not being able to provide more information because, as I said, it doesn't always happen.

I was using Ubuntu Studio before and it didn't happen.

Now I'm using Mint... Perhaps the kernel version is a factor.

I'm reporting this to document it.