Hey Guys,
I have a similar issue. I get the exact same error when saving Motion templates I create for FCPX (Generators and Transitions). Oddly, the templates save/export fine for use in FCPX. Like HarrisEdit, I have the latest version of Motion, and I also tried deleting prefs with no success. I haven't tried to uninstall yet. I keep my editing system pretty clean, but I do have a few plugins. I'm not using any plugins for my templates, but it still might be a good area of focus.
Here's the error and a little more system info:
Share Failed: The operation could not be completed because an error occurred while sharing (Timed out, server application never registered to receive message).
Mac Pro Late 2013
OSX 10.10.5
Motion 5.2.2
Plugins: Coremelt "xTools", FxFactory Pro, Digital Anarchy BB, Hitfilm Suite, Red Giant stuff, Neat Video.
Again, my templates export to FCPX fine, so it's not a big deal for me, but still a nuisance.
I hope this info' helps