HEY same exact thing here. Android OS usage going nuts here. I personally think its related to certain wifi / router setups.
When im on 3g/4g all day, it doesnt happen. On the days that I am stuck at home on wifi, the android OS usage starts again.
Ive already Odin'd back to MI7, took ota to MJE, rerooted, installed beans b5 and its still happening.
I think its a bug with samsung / verizon wifi. Many times I will wake up my screen and see my GPS / Wifi being used for no apparent reason even with all location services turned off. I also notice my wifi indicators being on when i turn my screen on. Then after i turn my screen on and sit at my home screen for a few seconds. It all magically stops.
Mind you, this is with no apps installed other than what is in beans stock and nova launcher.
You guys should monitor while off wifi and see what happens. It was the first thing that struck me when i was on a road trip for 12 hours. My battery life was exceptional. If it is the wifi causing problems, i wonder what it is specifically.