This is a follow up to a thread I posted on the forums (link text). Basically re-importing geometry from an FBX file is not updating the UV channels. See this video for a demonstration of what is happening - link text
The only workaround I have right now is to delete the object from the project entirely and import from fresh, which is not ideal.
Pleas make a copy of your project before trying this
If you delete your Intermediate, Saved, and Derived Data Cache from your main project folder this will force your project to recompile.
This will clear up any information that is left over from the first time you imported your .fbx. Effectively, this should allow for your .fbx to update and keep updating every time that you re-import.
These files are located in Unreal Projects > " Project Name " > and they will be within this first folder.
same issue here in 4.14.3 re-import and even deleting the object does not update the second UV’s (lightmap UV’s) … 1st uv’s ARE updated.
Deleted Intermediate and Saved dirs
The problem still persists with 4.15.1
Deleted the asset from the project and the Intermediate+Saved dir. Restarted the project and imported the file again but still the same UVs as before.
I had this same issue, but it’s because I still had “generate lightmap UVs” checked, so on re-import it was just reinterpreting my primary UV map. Once I took that off, both maps are fine.