Truphone SIM?

I have a Truphone SIM however, I cannot get it to work with the Karoo. I have confirmed that it is working (I tested it in my car and successfully received data).

• I have setup the APN per Truphone instructions
• With the SIM installed in the Karoo, I can see several Network operators when selecting that item in Settings / Cellular Data settings page
• When selecting Truphone 3G, the Karoo attempts to register with the network, but gives up eventually with an error, “Can’t connect to network, please try again later”
• When selecting AT&T 3G (which Truphone told me will work too as they are a partner network), I immediately get a “Registered to Network” acknowledgement, however after that goes away, there is no Network Operator identified as being connected to in the “Network operators” area of the / Cellular Data settings page.
• To test if perhaps that is a UI issue not providing the “AT&T 3G” label, with the device’s wifi disabled, I have setup a couple of test routes (test 01, test 02) in the Hammerhead dashboard to test if they will sync with the Karoo over the cell network -- regrettably they are not downloading to the device.

So… any ideas beyond the obvious that Truphone SIMs may not be compatible?