There is a bug in anim assets when it loose connection to some pins after save and reload.
For example I created such anim blueprint:
https://i.gyazo.com/8920d360b1de7c9d36c4ea28a9dc7cca.png
And after reload split pins became disconnected from bone transform nodes.
https://i.gyazo.com/5b85237d9f360a08edbecc2378dd5886.png
Only such configuration works for now