It appears that the Anim Instance class is no longer accessible. As a result, no animation blueprints made are accessible via blueprints - regardless of whether or not the skeletal mesh actually uses the BP, they're just not recognized. This is a regression from 4.22.3 (CL-7053642).
This was reported and tested in 4.23 (CL-7838574). This was reproduced in Main 4.24 (CL-7971874)
Results: No animation blueprint classes appear in the list.
Expected: Animation blueprints can be cast to
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-78806 in the post.