New Nebulae show their innards

[Treewyrm]

A lot of non-vanilla system in disco or those heavily modified have errors and missing properties for various objects. Technical quality has never been a particularly strong point of mod's content, rather the opposite. Ain't helped by plenty of bugs in Freelancer rendering. When encountering these inexplicable bugs what I did was to have an empty isolated test system, place the content affected there or better yet recreate it and test if the issue persists. For your particular case I'd have exclusion zone within nebula and have those large asteroids within it while ensuring their bounding box does not extend into the border of exclusion zone.

After all in old Omicron Iota I had those large base structures within the nebula and I hadn't any visual glitch that would show them from outside, same goes for Ravine base in 99 (or whatever it is called nowadays) and it's about the smallest nebula+exclusion with base inside I could do without having pop-up glitches.