I mine Zcash at nanopool for about 3 weeks now. and I found this.
The first 1 or 2 weeks, everything runs ok. Nanopool actual mine more zcash than flypool. Then, until recently, I saw one “pending” on 07.oct.2017 around 21:4x:xx, that payment was pending for more than 5hrs, and when I check again next morning, it was gone. I went to see the top miner and see if they have the same problem as I do, and yes, all of them, at the same time 7.oct.2017 around 21:4x:xx, that payment was pending as long as I do. The second time when I see this problem again, which happed on the next day at night time, I stop all my miner. That pending payment not lost. (go check yours, I’m sure yours lost too)
And other incident is, I don’t know if you realized or not. Your Balance freeze for couple hrs. The balance number just freeze there. This happened before, back then I don’t know what’s going on until I lost my pending payment, I realized it might be stolen hashes. I think nanopool use these 2 methods to steel your zcash. Those incidents happen mostly at night time. Mining in the morning seems ok.