From a glance, it looks like numFailedRenews is assigned in threadedContractMaintenance before any write calls. Did you hit a panic? Regardless, I'm not opposed to merging. My only change would be putting back all the types.BlockHeight. It's annoying, but better to be consistent when there's no real reason to change it.

I hit a deadlock when running contract maintenance. While debugging, I found that the map could be read from but couldn't be written to.
Regarding the types, I will put them back; however, I find it weird to use types.BlockHeight when semantically it's just a counter that is incremented every time a renewal fails.