Not a bug. I am guessing you joined your alliance sometime around December 6th or 7th, which means you had a cooldown timer to start the event before you could actually contribute to your alliance milestones. You need to be in an alliance for 14 days to be able to contribute. So you opened stuff before the timer was up and those points didn't count.
agree.
Opening PRIOR to being in Alliance for 14 days means those ONLY counted towards Realm-wide and Solo events (NOT Ally).
Once you hit 14 day time in Ally, then your subsequent 880 points started to contribute to there as well (but not retroactively for the earlier roughly 11,000 pts).