Just out of curiosity, are you using the appimage?
Maybe I'm wrong, but that could be the reason, as appimages create a temporary alternative path for system libraries files.
It also causes the GUIs of Calf plugins to be blank (you mentioned this error in another query).
Except for CalfFluidsynth, the rest of the fluidsynth plugins available for linux give me problems when creating templates that contain them, they crash Qtractor.
Just out of curiosity, are you using the appimage?
Maybe I'm wrong, but that could be the reason, as appimages create a temporary alternative path for system libraries files.
It also causes the GUIs of Calf plugins to be blank (you mentioned this error in another query).
Except for CalfFluidsynth, the rest of the fluidsynth plugins available for linux give me problems when creating templates that contain them, they crash Qtractor.
Try the installable version of Qtractor:
https://build.opensuse.org/package/show/home:rncbc/qtractor
In the list on the right are the .deb installers for ubuntu (and therefore mint)