With OpenGL rendering there is a flicker bug, that sometimes appears, I don't know exactly when, but it happens when displaying the NavMesh and in some scenes with heavy load I think.
Here is the NavMesh flicker example video, first normal scene, then switching on NavMesh render, flicker appears, then disabled NavMesh view and everything is normal:
https://duion.com/files/temp/bugs/openG ... avmesh.mp4
And here a flicker happening in a normal ingame scene, it happens on very few levels, this is a very big scene with lots of forest and groundCover elements, the flicker only happens sometimes, so sometimes you can launch the game and play the level fine, another time it has heavy flickering. When I decreased mesh render quality in graphic settings I could make it stop through that, my mesh render quality settings reduce the number of groundcover objects, maybe that is a hint, that it happens when there are too many objects or polygons to render, like the NavMesh that adds a lot of overhead:
Also you may notice the recordings in OpenGL are somehow upside down and mirrored in some way and I have no idea why, they were recorded with OBS and it normally works fine, but this only happens in OpenGL as well, maybe another bug.
I would suggest to replicate it with the NavMesh method, which is pretty reliable, the other thing happens very rarely. The issue exists for quite a while now and with multiple versions, but I ignored it so far, since I thought it was just something with the NavMesh display and maybe it is, but maybe those issues are related.