I have a Galaxy Tab Pro 12.2 rooted with Chainfire stock rom. I started getting random reboots soon after root and yes I did select yes when super su asked to disable knox. Never had a problem with this on a Note 4, S5, or Note 8. I tried most of what everyone has discussed except re-flash and factory reset. I also uninstalled super su, enabled knox, re-installed super su. But this time super su did not ask to disable knox. Re-enabling knox did not stop it. I installed xposed server crash tool and got the

Source: Random reboots after update – Pg. 6 | Samsung Galaxy Tab Pro 12.2, 10.1, 8.4