I recently setup My P Drive and Tools and discovered, that importing Proxies removes too much of the Prefix, resulting in an invalid Path and not being able to add Proxies. It looks like Object Builder just substrings the Path with the start being the length of the Textures Path. Problem is, that I have a different Textures Path setup which causes the issue.
Example: Instead of \DZ\characters\headgear\MxHelmet I now get \eadgear\MxHelmet
My Config of Object Builder: