What RlyDontKnow referred to was probably an already known issue with grass in relation to the Background Loader mode
nope, that one I already tracked down and fixed, I was curious whether it's loading or culling going mad there, but as it's not loading, it's most probably culling which doesn't make sense unless you have an undocumented config setting in your config that I added for testing purposes that forces a specific culler everywhere and have that set to default to enforce hardware culling.
now the big question is: why would culling be wrong?
that sector uses simple (software) frustum culling, so it's not driver related.
since it's not driver related and works everywhere else and there's no reason the position or bounding box of the grass would change in any way, it seems unlikely that's even the cause.
so... why else would it render incorrectly? I don't know :/
what you could do to help find the cause of the issue is:
1) try to add "PlaneShift.Loading.ForceCuller = crystalspace.culling.frustvis" to your planeshift.cfg ($HOME/.PlaneShift/planeshift.cfg) (just to be sure it's not a weird culler setting) - if it doesn't help, remove it again and do
2) set up
glIntercept (with OneFrameOnly set to false in the config, instead hit the log key again after the grass re-appeared) so we could check the gl calls and see whether something is off there.
(note that I just recommend that as I have no idea what could possibly go wrong besied culling for you and because you seem to be the only one to have it (in other words: no dev/tester can reproduce it which makes it likely it's a hardware/OS/driver combination causing the issue))
