I have my MidiHub connected to a USB Hub. It’s a quite powerful one (60W - 5A), USB 3.0 with its own power source. The times I had to switch the MidiHub off (i.e. for updating firmware, or whatever), all the devices -the ones in the USB Hub but also all the other ports, including Thunderbolt hard disks- got inmediatly disconnected.
Has been already reported a power issue like this?
I’m using a MacPro (trashcan) with High Sierra.