Brush issue - image goes blank [SOLVED]

EDIT: this was solved by installing libpng1.4.8, as it is required by Nuke, and using LD_PRELOAD to point to it.

I’m trying out the new brush tool in Mocha 2020 and when I go to paint the image disappears. I can paint the mask but the image will only reappear when another tool is selected.

OFX, Nuke, Linux (Kubuntu 19.10), Nividia 440