I had around 2250 Arena ranking points just before the last ranking period ended and was in Gold I. Now 2 hours later when I check my ranking after the ranking period reset my points are at 1988 Silver IV. I only have one defeat since I last checked (-12 points), so it looks like I lost 250 points out of nowhere.

I also did not receive a tier chest, and have not gotten any tier chests for multiple weeks. What's going on?