i do use the latest Blu_Spark v29 not official TWRP... i don't think it's Nova either, because i had the same version working perfectly on the previous build...it might be gapps, i'm thinking about changing to Beans, it officially supports 7.1.2
using bluspark TWRP too, the fingerprint and pin blocked happened just one time yesterday and never after or before, using Nova too.
@siankatabg any chance to implement Wakeblock? https://forum.xda-developers.com/nexus-6p/development/wakeblock-blocking-drain-late-t3526313
the rom is great, I tried all of them, this one is just exactly what i need! great job!!!