The Arrays -> Montage filter is crashes with this error:
Plug-in crashed: "gmic_gimp_qt" (/usr/lib/gimp/2.0/plug-ins/gmic_gimp_qt)
The dying plug-in may have messed up GIMP's internal state. You may want to save your images and restart GIMP to be on the safe side.
GMIC 2.6.7 - installed from the official deb package.
GIMP 2.10.12 - from Otto’s PPA
Kubuntu 18.04.3 64bit
What may be the problem?