I got a USB WiFi dongle from ThinkPenguin that I suspect was part of a bad
batch. After a series of emails where we triaged the problem and confirmed it
couldn't be solved, ThinkPenguin offered me a replacement. The original
dongle I ordered was this one:
https://www.thinkpenguin.com/gnu-linux/penguin-wireless-n-usb-adapter-w-external-antenna-gnu-linux-tpe-n150usbl
The replacement was this one:
https://www.thinkpenguin.com/gnu-linux/penguin-wireless-g-usb-adapter
... which worked and is a lot more convenient and portable that the big one.
From what I remember, the problem I was having with the first one was similar
to yours an the replacement worked fine.