I don't know about all of that, but it sounds like the ISBoxer Addon might not be enabled in game. Check that in your Addons list from character select? Something else to try is also hold Ctrl -- Ctrl+Shift+Alt+I -- and see if that works but Shift+Alt+I doesn't. The quick setup wizard sets up the actual WoW binding on Ctrl+Shift+Alt+I, when you press Shift+Alt+I -- to help demonstrate to the curious that your Hotkey does not need to match what it actually presses

So if the WoW binding (Ctrl+Shift+Alt+I) works, but the ISBoxer binding (Shift+Alt+I) doesn't, then it's an issue with ISBoxer loading its bindings. The only reason I can think of off the top of my head is if you installed ISBoxer to a different location than Inner Space, in which case you need to copy the files from the ISBoxer Scripts folder into the Inner Space Scripts folder.