External display flickers on one of the Mac ports

Solution 1:

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.