Only seeing ONE of two external HD's plugged into Apple Airport Extreme Here is the scenario:

I have TWO External TB drives.
They are both plugged into a Powered USB Hub.
That Powered USB Hub is plugged into the back of my Airport Extreme.
I can only see one.
They have both been formatted with OS Extended (journaled).
Each are visible if only ONE is plugged in (i.e.  TB_A can be seen if just TB_A is plugged in, and TB_B can be seen if TB_B is the only one plugged in)

Does anyone have any ideas?  So frustrated because it doesn't make much sense.
I've run into a similar problem using two flash drives, same size, same manufacturer. For whatever reason, the hub doesn't differentiate between the two. Try right-clicking on the drive that you can see and renaming it from "manufacturer xxxxx" or whatever it's called to something unique like "external drive A". Then shut down the entire setup (Mac, hub, Airport in that order) and restart everything (Airport, hub, Mac). That may help.