My ranked scoe just disappeared

I’m in B5. Been working my way up 15-25 points at a time. I was up to about 550 or 575 when my winning streak ended. Suddenly my score was down to about 70 after only ONE LOSS! What is the issue here? Is this how ranked works or is this a bug?

What happened is probably you got disconnect or just maybe the game doesnt want you to climb out of bronze 5 yet. See bronze 5 is an open end league like masters, while masters can earn more points, bronze 5 players can’t go lower than 0, that’s why you can’t really see where your " true rank" currently is. The bigger the difference of your MMR to the bronze 5 rank is, the less points you are earning. Your goal should be bringing your MMR to the Bronze 5 level first to the point when you start earning 200 points per loose/ win.