It's this bug in Blender: https://developer.blender.org/T58093
It's easy to fix. Open the .dae in a text editor and search for lines like
and replace them with
You can do it automatically with find-replace <texture ⇒ <texture texcoord="uv".
Technically this fix is still wrong, you're supposed to also insert something in the <bind_material> element. But Blender doesn't care, it will work anyway
It doesn't even care what name you put in the texcoord, you can use texcoord="whatever" and it will still work. If you're making new .daes to upload you should still export from an up-to-date Blender though.
It's easy to fix. Open the .dae in a text editor and search for lines like
Code:
<texture texture="something"/>and replace them with
Code:
<texture texcoord="uv" texture="something"/>You can do it automatically with find-replace <texture ⇒ <texture texcoord="uv".
Technically this fix is still wrong, you're supposed to also insert something in the <bind_material> element. But Blender doesn't care, it will work anyway
It doesn't even care what name you put in the texcoord, you can use texcoord="whatever" and it will still work. If you're making new .daes to upload you should still export from an up-to-date Blender though.