Hmm... this is a wild guess, but maybe there's something about USB 3.1 Gen 2 that doesn't work well with those devices you tried (all external are 3.1 gen 2). These are high speed ports, which I imagine are much more sensitive to hokey products.

There are USB 2.0 headers on board (pg 16 of this TPS report :) ), so if you wanted to try, you could expose a port and try connecting there using a connector like this.