Alex,
I agree with Kevin. Ensure that the asset isn't still open for edit. I've done that before too and got really confused when I went looking for it in Surveyor!
A couple of hints too regarding night mode and stuff.
Sometimes the creator has created a night mode director which is referred to in the config.txt. This is okay, but the problem is not all the textures, or even a night-mode mesh file are copied into the nigh-mode directory. This can cause errors and is easily fixed. I found that if I check the main folder for the asset, that the referenced textures and mesh files were there. I simply moved them to the correct folder and everything worked.
In your case, the PM2IM tool should fix your problem. Sometimes it can't though and I'm not sure why.
John