I had an issue earlier where i was trying to set charge limit in app after car plugged in so car fully awake.
App was trying to connect for longer than would be reasonable- probably 1-2 minutes.
I then closed the app (latest iOS) and restarted at which point the app immediately connected.
What I did notice and never had seen before, was that the app refreshed itself in 2 stages.
Unfortunately when the car did start to charge we got a car started to charge message about every minute. This went to all linked apps so not an individual app issue.
I had to stop and restart the charge to sort.