You just need to make sure that *every *material of that skeletal mesh has a Don UV material node connected to it.
The sample project uses a master material for the skeletal mesh which all the material slots derive from, so it only adds the node once. I’m assuming your material slots are all independent, so each and every one needs to add the correct Don UV node inside of them. Paint will automatically be routed to all material slots that carry a matching Don UV node for the active layer being painted.
If you’re already set this up and it is still not working, screenshot snippets of your material would help!
And yes, do feel free to share your creations on this thread!
