We had it last night (me and my team). Basically we kept closing and starting UPlay. Eventually it connected for each one and we could group up, but it was a pain.
Same for me and lot of my mates, it's broken since the maintenance, it sometimes does not connect...
and when everything works, i starts a R6S party and it displays current connection...
I've had the same problem, and so does my mate that we usually play with...
I popped a booster and we were planning on playing together, but since it didn't work we ended up playing another game instead, so I sort of wasted my booster...
Any chance ubisoft can compensate me with a new one? :/