Updated the app to v1.0.1 and I removed the ability to enable KNOX notifications (not that many people would want to anyway). I did this because I was testing my own app, toggling disable and enable a ton of times and when I rebooted next, the phone wouldn't boot. Now, my next reboot was caused by me issuing an "adb reboot nvflash" to make the phone backup it's EFS and it seemed successful. Since I can't identify if it was the adb command that caused it or the enable button that caused it, I'm doing this as a preventative measure for now.
When I enabled KNOX, it gave me a message telling me I should reboot as a security measure due to an app (something like that) and I assume it's because it knew an app turned off KNOX at some point. I ignored it, maybe that was the cause, I'm not sure. My phone is soft bricked at this point, and I tried everything - using the .pit file posted by Garwynn for the Sprint version in combination with a stock tar flash numerous times with and without the Nand Erase All option checked (I tried
this based on this guide, obviously didn't use any of the Verizon files), data/cache wipes in recovery - nothing. Nothing will allow the phone to boot, it always comes up and says "Process system is not responding" and then reboots itself, Bootloader says the current binary is Samsung Official but system status is custom, Odin can't even change that.
While I'm sure it's nothing to worry about, I just don't want this to potentially happen to anyone else.