I've noticed a weird quirk in how the daily limit on the PQ works. You are only allowed to play 6 rounds before the game tells you its the limit of the day, and you'll have to wait until next day to play 6 more rounds. But for some reason, plays count between days. So if you play 3 runs on one day, and another 3 on another, it will kick you on the end of the 3rd round, even though more than 24 hours have passed. I have done 5 runs 2 days ago, and today i did a single round, but my chara was denied further runs for the day. this have happened on all the mules i used as well, so it's not a single case, and i have recreated it as well afterwards.
I've had the exact same happen to me. Did 5 PQ runs yesterday, decided to call it quits. Wanted to play it again today and after 1 run I got kicked out telling me I had already played 6 times today.