External display flickers on one of the Mac ports So I got a usb-c adapter/hub that gives me VGA, HDMI and some USB ports. If I connect it to one of my Pro's two ports, it works fine. If I connect it to the other, both VGA and HDMI start flickering. The port on the Mac itself is fine since I tried it with a different adapter. 

Can anyone give me a hint on why such inconsistency might exist. Could it be because one port is USB 3.0 and the other is (in my understanding) USB 3.1?

Update 1: I have a Macbook Pro 13inch 2017 no touchbar and I used this dongle: https://www.amazon.com/gp/product/B0749JXV6R/ref=oh_aui_detailpage_o00_s00?ie=UTF8&amp;psc=1

Update 2 Just tried it with a different Macbook Pro (13inch, with touchbar), same issue persists. The hub only works with one of the ports as if the two ports are somehow different.
The 13" MacBook Pro has two Thunderbolt 3 ports with support for USB 3.1.  USB-C is the connector type.  There are no 3.0 ports at all.



The flickering you are experiencing sounds like a clock sync issue  (TDMS clock for the display, not the clock that keeps system time).

First thing I would try is rebooting with the hub/dock connected to the port that's giving you trouble.  If the problem goes away, then you've narrowed down the problem.

If it remains, you may have a hardware issue.  Before taking it into Apple, however, it might be a good idea to try out a different video adapter.