I've discovered interesting thing about KNOX. Installed the KNOX software on my Note 3. Worked nice. When I switched my sim card to a card that does not have GSM connectivity (only 3g/HSPA+, since that card is for free Internet access service called Aero2 in Poland) everything related to KNOX was crashing. The software itself couldnt launch properly and was inaccessible, all apps running by default in the KNOX shell crashed. Lots of errors, lots of force close messages, knox not working. Switched my sim card back to my normal one - errors gone, everything works fine. Im not an expert, my phone wasn't rooted because I upgraded to new bootloader by mistake and don't want to loose warranty, but this could possibly point that sim card itself could affect KNOX in some way.
Sim card/GSM connectivity affects KNOX software, might be a clue where to search for resetting knox.