zmod attach issue and weird lightbar glass behavior in-game

So I'm working on this DHS pack and I'm running into some problems with the lightbar glass for some reason. I'm honestly not sure how to explain this one... So here are some videos demonstrating the problem.

zmod attach problem:

Weird behavior in-game (axes to world):

Weird behavior in-game (axes centered to object):

If you look closely at the second video, you can see that even when the vehicle is stationary the lightbar glass isn't properly positioned (modules are clipping through the top), even though it displays correctly in both OpenIV and zmod. When the vehicle starts moving, the glass literally starts spinning in a circle around the vehicle and comes to rest wherever it feels like. I attempted to rectify this issue in zmod by attaching the glass to the lightbar base but that doesn't work either. I also tried attaching the glass to the base in the original and unmodified file I downloaded from LSPDFR.com and the same issue happened. Repairing the car does nothing to change the position of the glass. I also tried centering the axes of the glass to the object, which resulted in the glass spinning around its original location. If you want a link to the z3d for testing or something let me know and I'll provide it via PM.

I don't really want to change the lightbar at this point so any assistance would be helpful.

Quote from Slendis

Someone, a long time ago, told me that happens when you attach something that is too high poly. Not sure how correct it is, but that is the first thing that comes to memory.

Thanks for the response. I managed to get it fixed by reimporting the glass and keeping it uncompounded with no LODs but that's obviously not ideal. I'll try reducing the polys and see if that works.