This occurs for any place instance I attempt to open. It does not matter if it is an uploaded one, a Roblox template, or a local place file. That said, I have DMed you a template file where this occurred for me if it helps.
These users are also experiencing this issue FWIW:
This warning happens when internal engine logic tries to reference Workspace.MeshPartHeadsAndAccessories from outside of the DataModel. This is almost always a bug, but I can’t seem to reproduce the issue myself.
I’m thinking it’s probably one of your plugins. Would you be able to provide a list of installed plugins?
Perhaps it could be because it loads in an R15 avatar in a ViewportFrame and/or WorldModel within a plugin window?
It did not print this warning until the last few days FWIW, so this warning message is a relatively new if unintended. Plugin also seems to still work fine.
Thanks for your help investigating this! I really appreciate it.
The good news is that I fixed this issue already and it will be released in ~2 weeks.
Until then, I’ll shut off the warning. You’ll need to restart Roblox Studio.