Ver 1.7 does not report error. DEMO showed everything correctly in floating UI. If i’d have to take a swipe at it, might be part where you transfer UVs from your app to Blender. Might be worth considering that there are a lot of instanced geometry as is often the case with production. note: I only choose 1 of each instance.
Another error. This time minimal settings, completely distort the UV. Something is not adding up:
