After further investigation, I found the profile sync doesn't work at all when redirecting to any server (Tested creating new profiles via about:profiles in Firefox, setting to different shared folders). Works fine if the profile is stored locally, so I have put a workaround in place by adding -profile "C:\Profile Path" which creates the users profile locally. Thankfully only one user uses the Sync and they only have 2 VDA's, so not much of a hassle. I have also tested by creating a share on my own PC, setting up a new profile and pointing to that share, and the sync still doesn't work, as such I think this may be an issue introduced in ver. 94.