I have read through all 35+ pages of replies of the monster thread started about this issue back in December 2013. It has since been locked, it seems, and I am unable to post my issues on that so I am forced to create a new post.
I have a Rev A03 version of the UP3214 (Bought March 2015) and although I do not suffer from the split screen issue when running MST mode at 60Hz, I do almost always still get the dreaded blank screen / no power when resuming from standby.
UP3214Q Rev A03 firmware
MSI GTX970 Gaming
Nvidia 344.75 drivers (latest as of this writing 4/19/2015)