i've tried with android 5.1.30 and Gateway 1.4.1_154.0143 with the steps above - china, scan, see hub#, switch to SG, connect the hub.
problem is, after connecting "successfully" the hub, i'm not able to see the hub in the app. but subdevices like door sensors, motion sensors etc added themselves to my app list (without having to reset the subdevices). the sensors work as in able to see when motion is detected, when door is open/close etc but couldn't setup automation.
couldn't setup automation from the subdevices, nor from the hub - because the hub is still not visible in the list.
tried few more times to reset the hub, but same issue. in the end i put everything back to china server for the moment till the next "update"