I have several maps that I've downloaded from the workshop, and I've manually loaded them in Jazztronauts. This seems to have broken them for use outside of Jazztronauts.

For example, GM_Traincity_V2. I have the map, I've played it in Jazztronauts, but now I can't play it in Sandbox mode, due to missing models and textures everywhere. Which is odd, because I have all the content needed, mounted. HL2, EP2, CSS, the works.

The map loads fine in Jazztronauts. It doesn't in Sandbox.

This has also affected some maps I haven't played in Jazztronauts... GM_Pamtob for example. Most everything loads, aside from the ground texture, which I believe is an EP2 asset... probably used in one of the maps I loaded with Jazztronauts.

Does Jazztronauts build its own cache of files somewhere? Something might be confusing GMod.