I’ve used imps at various times on iPhone hotspots with success.
If the light’s green it’s connected. What are you seeing/not seeing in the IDE? Note that there can be a several second lag on the first traffic after an idle period before the data starts flowing with any 3G network.
Are you sure you were looking at the right device in the IDE? ie, have browser open on device on normal wifi network, see log messages. Blinkup imp to new network, do you see log messages?