I can't level up the battle pass points by earning XP because my rank is S999.

I can't level up the battle pass points by earning XP because my rank is S999. This happened 2 days ago.

At the beginning, I can earn BP points by earning XP. And some ppl I know with the rank S999 are facing the same issue. Some of them even can't get BP points by earning XP when season 1 came out. 

I guess there might be a XP cap after S999. When I reach the cap, I can't earn XP anymore.