This was reported in 4.3 in that the sand layer in the vehicle example could not be painted on and info has it it’s a glitch in the master material and passed to the instance. I took a look to see if it’s an easy fix but beyond my current pay grade. If someone has gone and fixed it I would love to have a working copy as I’ve a project in long last that I can make use of it.
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How about a long last fix please ? 