USB file transfer weirdness

[Malevolence]

I plug my cable into the front USB 3.1 Gen 2 port and the phone (Android) isn't recognised, it charges via that port but no matter what I do it won't recognise it to transfer files on those ports. I don't even get the little drop down menu to select the transfer protocols. The ports function just fine with USB drives and the like.

However, if I plug the same cable into the ports on the back panel (both 3.1 Gen 1 and 3.1 Gen 2 (Red)) it works like a charm.

Does anyone know what might be happening here?

 

[marc2003]

If you've got 2 x USB ports per internal header, is there something plugged in the other port? I often have issues where I can only run one device at a time instead of 2. Unplug the other before plugging in and it's fine. My issues are probably cheap hardware/case related though..