Thanks for contacting us! I am sorry this is not working as expected.
Based on your description of this behaivor our first step is to get some additional information from the Apple system in the working and non-working configurations to see exactly how the computer is ( or is not ) detecting the connected USB hub.
If you would, please keep the dock connected to the front port of the Apple computer, where the hub is working and connected USB devices are detected, then run and attach the output of our diagnostic utility PlugDebug ( http://plugable.com/support/plugdebug ) to an email to ‘firstname.lastname@example.org’ with the subject line ‘Ticket #381434 - Attention Pat’ as this will allow us to examine some log files from your system to help determine the next steps. I recommend appending “-hub_front” to the end of the zip file ( before the .zip ) extension to clarify this file is in the working position.
Next, please connect the USB hub to the back of the docking station and verify the devices are not detected, then re-run the PlugDebug utility as above, please append “-hub_back” to the file name and attach to the reply email to our support team.
I will examine and compare the working and non-working log files and see if this provides any information that may help to work around or duplicate this issue on our test computers.