Give a soft reset a try and see if it helps. Power down the 950xl. Press and hold the power button and the down volume button until you feel TWO vibrations and then release so the phone can boot.
If this doesn't work, backup your phone and do a hard reset and restore and see what happens.
Some don't recommend doing a hard reset after an OS update but I do and have found the problems that others have I don't. Just saying.