Mouse pointer disappears at "Klei" splash screen, and does not reappear for game interface.
Only happens on full screen, in windowed mode mouse pointer shows at all times.
I only this moment discovered if one uses the Linux snipping tool, it forces(?) the cursor to re-appear.
Launch game via Steam. Have graphics configured for "full screen 1920x1080 120hz" and UI set to 90% scale.