Hi!!!
I found a detail in normal maps. Maybe will be a EEVEE limitation…
If you use a mirror modifier with offset UV, the “other side” invert the Y channel.
I
Uvs
We’re using overlap uvs for save memory in game engines.
In cycles, sketchfab works fine.
This fix work fine!!!
A vertex color for invert only Green Channel in the offset uv
It’s not a bug report 
, is only a doubt about eevee behaviour.
Eevee is supposed to match Cycles here, if it’s doing something different it’s a bug.
Yes, cycles do it well.
It’s a bug… 
Can confirm, mirrored uv’s is very commonly used in games.
Stumbled on this issue myself today. (look at teeth)
Yes, same problem here.
Ok, I found 1 more clue.
The Green channel flipped could be caused by the “inverted shell”.
Check it out: https://blenderartists.org/t/addon-flipped-uvs-selector/668111
Cycles fix this problem, EEVEE not yet.
Maybe @fclem can confirm if it’s a bug?
So… Is there any plans on fixing it? It’s still present in blender-2.80-c3d46694e21
Hmm, i still have this issue
