Same just happened to me after flashing 4.4.1 OTA.zip and SuperSu 1.80 with TWRP. It came up immediately upon boot.
Will try to install OTA 4.4.2 and report back ASAP
Pressed install & restart on OTA. It upgraded through TWRP.
Root & Custom recovery were lost as expected.
Reinstalled TWRP and SuperSU, all appears to be good.