Running 12.0 nightly 20231213, the Embruary skin is marked as incompatible. I reinstalled the 20231211 build and it's fine.
Not sure if this is going to be an incompatibility moving forward or if maybe some version bit got set somewhere marking it as incompatible. Not sure if Embruary is even still being developed at all, so I don't know if there's a chance of it catching up.