Mirroring Gear Prevents Selecting

If landing gear is mirrored (seemingly regardless of the gear settings, and whether the gear is mirrored normally or radially), it prevents selecting any parts of the vehicle that existed before the mirroring. New parts can be added normally, but do not interact with the parts that existed before the mirroring (they do not appear to collide with the original parts, and they can also not be attached). There seems to be no way to prevent or revert this. The bug appears to be the same both on the stable and beta builds.

The attached screenshot also shows that for some reason, one of the gear legs is not deployed, and it also fails to deploy once spawned in. I'm not sure if this is related to the previous bug.