I use right click navigation with the Intuos tablet and Pro Pen 2. CTRL-right click to zoom. When zooming if I release the CTRL key before the right click then the model snaps back to it’s state before zooming. If I release the right click before the CTRL-key then the zoom works as intended. The snap back usually happens when I’m working too fast or tired. Also when I’ve navigating with a very large model (> 20 M polys). I have to wait a fraction of a second for the display to catch up. Given that you say it works 90% of the time my thought is maybe to look closely at the order which you press and release buttons/keys/pen presses. Good luck.