I think this is a bug but not sure exactly where it is. I went camping this weekend and took my mobile WF station with me. The place I went did not have any type of internet access. I figured that the worst case would be I would only see the current weather conditions on my tablet or phone. I powered up the hub and my Samsung Galaxy Tab E and opened the app. The hub light went from red to blue but I couldn’t see any current weather data from either AIR or SKY. The next morning I took the hub, AIR, and tablet with me on a bike ride and when I found a spot with cellular access I powered everything up and could read the data from AIR (the SKY was obviously out of range). I even received a notice on my phone that AIR - Mobile was now online. When I got back to my RV the hub started displaying info from SKY as well.
Just before breaking camp to come home I decided to power cycle the tablet and hub to see if it would connect without internet access and was met with the same issue. I had to wait to get to somewhere with internet coverage to get the sensor information to display on the app.
I thought it was supposed to work without an internet connection so am a bit confused. I’m not sure if this is an app or hub issue. Unfortunately, I didn’t think of powering up my iPad mini to see if it would work.