The Done vs Next thing is something I saw a lot. I think it’s just a weirdness of ST. Done and Save have no actual difference at this point, I don’t think. I’ve seen that in my version as well and it never really mattered.
The second screen just means it saved the ip and is waiting for the hubaction to get sent and the response delivered.
I’d guess a networking issue between your apex and your ST hub at this point. Everything seems in order otherwise based on your logs. It asked ST to send the hubaction and is waiting for the response to be delivered. Either your apex didn’t receive it, your apex didn’t respond to it, or ST never sent it in the first place. I don’t have any way of confirming that the hubaction is sent that I know of.
If this is a bug in the smartapp, I’m not sure how to find it. I’ll see if I can whip up something in CoRE to test connectivity.