I too recently quit Polo. Had an odd issue where I closed all of my margin positions at a small profit, but Polo still thinks I have open positions:

Total Margin Value 0.01475918 BTC
Unrealized P/L 0.00000000 BTC
Unrealized Lending Fees -0.00000004 BTC
Net Value 0.01475914 BTC
Total Borrowed Value 0.02176298 BTC

Their system is very buggy IMO. I fear the worst...