Since Firefox 56, Xmarks was not working anymore, I also could not get the beta working, so I decided a few weeks back to install Firefox 55 again.
But today, My Xmarks was automatically updated to 22.214.171.124, and stopped synchronizing.
I installed latest version of Firefox again, but also that didn’t help me. It just keep synchronizing, but it changed nothing on the server…
I was busy with it many hours, finally it’s working…
I could get it working like this:
Installed latest version of Firefox and Xmarks
Log in to Xmarks
Manual upload my bookmarks to the server again (advanced tab)
After that, synchronizing works again like it always worked before.
I really hope my problems with Xmarks are over now, I post it in case someone has same problem, and many thanx to the Xmarks team for this Webextension version