Here's my story...
Received my new UK spec SM-P900 Note Pro 12.2, ran through the initial setup, performed two OTA upgrades to KOT49H.P900XXUANI1, then attempted to flash SU using Odin 3.07 using the various instructions on this forum. Result: failed cache flash and soft brick!
Used Keis 3 to recover the tablet which took two hours! After more reading I discovered the quick boot recovery flash method, so re-attempted on a different PC, with exactly the same result. Re-flashed the boot, tried again, fail, again, fail, etc, etc. Various permutations of PCs, Odin versions and USB ports were tried.
Concluded that the Odin method was NEVER going to work, so had a rethink. Used Odin to flash TWRP v2.8. Downloaded the latest SU-BETA v2.7 flash for TWRP (not Odin), copied it to the root of the tablet SD and then flashed it with TWRP. Worked first time with no messing about!!!
Booted, ran SU and upgraded to Premium, disabled KNOX from within SU. Tablet locked up. Booted, re-ran SU, disabled KNOX again, this time successfully. Ran Titanium, filtered with KNOX and froze all occurrences, then de-installed KNOX completely.
Lesson learnt... DO NOT use Odin to flash SU on a P900 !