This is a known issue. I had reported it to Bluebeam Support and this is what they told me. I did what they suggested and it worked - better - but wasn't really functional for me. It runs better in Bootcamp for me. This is copied from my Support email:
As it happens, we are familiar with the strange behavior you described. This appears to be a consequence of how Parallels works (or doesn't work) with our Skia-based renderers.
Officially, this issue falls into the scope of Parallels-related issues that Bluebeam does not support, but through trial-and-error, we've identified that this issue does not impact our Legacy (GDI) rendering engine. Switching to this renderer has helped other Parallels users.
Can you try changing the rendering engine over to GDI, and let me know if that helps? Follow these steps to do so:
- Open Revu.
- In the menu bar, select Revu → Preferences.
- On the left, select Advanced, and up top, select 2D Rendering.
- Change the value of the dropdown menu next to Rendering Engine to "Legacy (GDI)".
- Click OK. Try reproducing the flipping issue.