I have a couple of those here. Is there a jumper inside the chassis? If it is there try to put it on one of the contacts, and repeat the association that way with the chassis left open, after the association is completed put the cover back on... Or something. Or remove it, or put it on a different ...

Works nicely also on a linux install from current git (not on rpi), same host for plex server and domoticz (IPs both set to 127.0.0.1).
Thanks!