I agree it should be a bug but why a guy choosing an specifc instance ( for example Taral V hard mode only) joining alone and getting a pug group is getting the daily reward and a full group not?. I dont understand, is just silly. Group finder rewards pug and not full groups of friends?. We must be 3 friends + 1 pug to get the daily reward?. Is non sense at all.
As others have said, if your friend got rewarded when he solo q'd and selected just Taral V then THAT is the bug. There is no discrimination between 4 man groups and pugs: if you queue randomly you should
get the rewards, if you don't you shouldn't
. One bug where somebody got the reward when they shouldn't have doesn't mean that there is anything else going on other than something caused your friend to be incorrectly rewarded.
We did a random HM about an hour ago with a 4-man group, got assigned False Emperor and cleared it with no issues.
I suppose one other thing that might be at fault is that killing the last boss isn't always the end of the flashpoint - they have added an additional checkpoint to many of them to fix issues with people dying and then not getting the reward. So... make sure that the Flashpoint quest that you are doing is updating as you go along and that you do every step of it instead of just killing the last boss and immediately exiting the area.