FIll .... what i have seemed to notice is that if you invite more than 1 person, in your case a 3some, and one of those accepts their invite before an invite is sent to the third person, you guys won't all see each other. I fyou all don't see 3 people on the invite screen, you will never get all three on the first tee.
What i try to do is send all the invites as quickly as i can. And when i'm receiving an invite for a MP round, i usally wait 10-15 seconds b4 i accept ... just in case i'm the first person invited. that should give the host time to invite the other players b4 i accept. It's only seemed to be a problem for the last couple of weeks, but that's my thinking, for what it's worth.
Jeff