You're not alone. Polo was my goto exchange for a long time, only using other exchanges when something wasn't being traded on polo.
Each week there is more fud from polo regarding wallets that need updating or intervention from developers. I am very skeptical of the excuses since like you pointed out, other exchanges aren't having problems with withdrawals.
I don't know what their as angle is but time has come to be very leary of leaving large amounts there.
I forget where I read it, but I came across an article that said when Ethereum exploded, so did their trade volume and they were not ready. Which makes sense. I imagine they are severely understaffed, they even dropped the trollbox to increase streamability, but I just don't think their servers were prepared to handle all the traffic.