I use the MacBook Pro's monitor and two HP Envy 27" 4K monitors (one via USB-C, the other via Mini DisplayPort) all running simultaneously (not mirrored) without any issues.
[doublepost=1504157336][/doublepost]OWC's site has a driver update that might help with that.
If not, it's supposed to be for iPad charging and for using the Apple SuperDrive.
https://www.owcdigital.com/assets/products/thunderbolt-3-dock/OWC-Thunderbolt-Dock-Driver.dmg.zip
ended up ordering belkin. both belkin and my new 13 inch MBP coming early next week. cant wait!