I got a reply from Nanopool support on this issue yesterday. They are pointing to the Sia bug and the high difficulty. If this is true things should pick up after the block height reaches 139000. The calculators are saying that should happen around 3-4 days from now. I happen to think this is not completely true. They are mining substantially less blocks than other pools and the difficulty is the same for everyone. So... what to do until things improve?
I have been dual mining with Claymore so I wrote a Bash script that monitors my 6 hour hash rate and switches the pool to SiaMining when it gets high enough, then switches back to Nanopool when it gets too low. This keeps my 6 hour hash rate alive and makes me eligible for Block Rewards but also gives me an opportunity to mine into a PPS pool without missing the rewards from Nanopool. This means that every 3 hours or so, I jump over to a different pool and mine there for about 2 hours. Its working well and I got typical rewards from all the blocks mined in the last 24 hours plus a few bonus coins from SiaMining.
I am a few days away from a payout on Nanopool so after I reach it, I think I will go over to SiaMining until things improve at Nanopool.