There are issues with Xpresso which I reported to Maxon but at the end it looks that these issues are caused by Octane plugin.
First issue :
If Octane tag is used in Xpresso object, changing reference of that object to another that has the same User Data menus cause that all connections are lost.
Next issue :
If Object has Octane tag and some of its parameters are used in HUD which is grouped it will not load in XRef - Xref will show individual HUD elements but not Group :
It all works fine if Objects doesn't use Octane tags
EDIT : Sorry, but after investigating 2nd issue was caused by C4D interface issue when was used custom arrangement of panels like perspective view on the top right side.