Monitor model = U2414Hb (x2)
Monitor revision number = A03
Monitor 20 digit alphanumeric serial number = CN-0R9F1P-41261-4CO-4CML, CN-0R9F1+-74261-4CO-4ADL
Specific setup. Example =

* The SP3 (Surface Pro 3) dock is using its 48w power cable
* #1 U2414H has DP 1.2 Enabled in the OSD (On Screen Display)
* SP3 Dock mDP out --> StarTech mDP to DP cable --> #1 U2414H DP in (far left)
* #1 U2414H DP Out MST 1.2 --> StarTech DP to mDP cable --> #2 U2414H mDP in

Everything works fine so long as as I have the originating mDP cable plugged into the SP3 itself but when I plug it into the dock Win8.1 does not recognize either of the two monitors.

I spoke with a lady at Surface support and she says it's Dell's problem...I'm not sure how that is when the SP3 recognizes the device when plugged in directly but not when it's plugged into the dock.  I'm suspecting dock is the issue and MS will have to provide new firmware but that's not what MS's stance is...