Hi smidigi,
Upside-down views are almost always traced back to image effects on your scene camera. Tenkoku adds a few effects to your camera, automatically, depending on the settings you use. To debug this screen flip please try the following...
1) play your scene as normal.
2) while playing, disable all non-tenkoku image effects.
3) disable the Tenkoku 'use temporal aliasing' function in 'Configuration'.
4) disable the 'Calculate light rays' function under 'Atmospherics'.
5) disable the 'Tenkoku Sky Fog component on your scene camera.
We're looking for the point at which the screen flips back to proper view. Once I know where the bug is I may be able to code a fix for you.
If the above doesn't help and the screen is still upside down, I would also make sure that MSAA is turned off in your Unity Settings. Go to Edit-->ProjectSettings-->Quality and disable 'antialiasing', then restart Unity and try playing your scene again.
Let me know if this helps or if you still have trouble!