Bug report - "Challenge Accepted" achievement won't trigger with "Friendship Rules"

I completed “Challenge Accepted” at the same time as “Friendship Rules”. Friendship rules triggered, Challenge Accepted did not. I was able to work around it by leveling up another challenge under the “Challenge Accepted” category. Just putting this here in the off chance someone else has the same set of circumstances, or there is a more general “multiple achievements won’t trigger off one event” bug.