After updating, my character started (usually) holding things in their right hand, despite my preferences.

This doesn't occur 100% of the time (I never know what I'm going to get, but it's usually ending up right-handed for whatever reason).

Toggling between left and right-handed a few times, doesn't cause any visual change.

This sometimes seems to correct itself when going to the Nether (at least temporarily) – so loading a world has a chance to make it work appropriately.