Denied access to mesh UV's. Says 'Read/Write enabled is false' but it's not. What do?

Trying to randomise mesh UV's because I have props that share a material atlas in order to be able to give them a random texture upon scene loading. Read/Write is enabled in import settings, the gameobjects are not prefabs (although initially they were and it didn't make a difference) and not meshcombined.

I get a weird error that claims read/write is disabled. But it's not.

Is this the usual Unity 2+2=5 kind of thing or am I missing something? Please help

 

Fixed it. For anyone googling in the far distant future:

I needed to disable static batching.

 

"isReadable" property might be coming from another source: The error message indicates that the "isReadable" flag is set to false, which means that the mesh is not readable. However, even if this property is correctly set in your mesh, it might be coming from another source. In this case, make sure that the "Read/Write Enabled" property is checked in the "Mesh" section.