Hello. How can i fix this importing issues? I did everything i saw in import tutorials - uv maps, set channels for lightmapping etc., everything…but still there are problems…building gives errors, says object has overlapping uvs, but i checked all uvs…how i can fix this?
If your uv’s are really poorly done;
- They are mirrored.
- Overlapping themselves.
- Outside the UV 0-1 space.
then yea, you will get errors.
This could have easily be solved with a simple “ue4 lightmap tutorial” on google though 
which would have given you:
to just name two.
Your description sounds like you may be experiencing multiple problems, so you probably need multiple answers to fully resolve your errors.
As for the overlapping UVs, that is something I have struggled with for a long time, too. Many of the tutorials I have followed failed to draw attention to the “Generate lightmap UVs” check box in the static mesh editor. If you have this turned [on], it doesn’t matter if you manually unwrapped your UVs on your own- UE4 will just ignore them and generate its own (often causing the overlapping UVs).
If you have manually unwrapped your UVs for lightmap purposes, make sure that “generate lightmap UVs” is turned off and your lightmap is set to the intended channel. You will need to hit “apply changes” after toggling this checkbox. Hope that helps.
thats not true, ue4 cannot generate new uv’s for meshes. it will always look at one of the already available uv-channels and just reorder that.
2nd part of your comment is true though
Perhaps my choice of words was incorrect. What you said about 'reorder’ing UVs is what I am referring to.
While in the static mesh editor, if you are viewing your UVs, I am talking about how the UVs are rearranged to generate new lightmaps (provided you have that checkbox checked ON).
thanks for everydoby, i will try your advices and reply to you