I've narrowed down a bug with downloading my Vivosmart4 to Connect App on Android.
If I keep bluetooth off for several days to save power, then the connect app will get stuck trying to download.
If only a day or two of data then no problem.
Resetting phone, clearing app cache or data, removing and reinstalling app, none of those fix it.
The only way I've managed to clear the blockage is to connect to a PC, next day Android downloads work fine again. But I don't have a home PC so this isn't a valid solution.
Paul