Pairing with my LG headphones and the forerunner 955 has not been any issue.
Though, when my watch tries to connect, I hear on the headphones, that it infinitely connects and disconnects at a rate of 1Hz, while the watch keeps displaying "searching for....".
There are no connection issues with any other device and I already tried all the obvious stuff:
restarting watch, repairing with headphones after removing connection, checked for other potential bluetooth connections (phone and so on).