Yes, your summary of 1, 2 and 3 is correct.
a) The permission message appeared only once, many days ago. Since then, it has not appeared, despite being in the blocks.
b) Correct.
c) When the “scan” button is clicked the second and subsequent times, the listpicker is immediately cleared, the message “Scanning, please wait” appears briefly (for perhaps 1/4 second) then disappears.
After that, nothing happens. The listpicker remains empty.
Strangely, when run in the Companion, pressing “Scan” does not clear the listpicker immediately. The previously obtained list persists during the scan operation and is only cleared when populated by the latest data.
The apk seems to run in other Android devices, such as a Samsung Galaxy 3 and 5 and a Vivo X20A, so it looks like the cheap Lenovo Tab is not acting like a good citizen. Perhaps it’s a memory issue, but this would not explain why it runs happily in the Companion, but not when compiled.
this is normal, because the user only has to grant the permission once
Ah, OK, that makes sense.
so it seems to be a device specific issue
It looks that way, but I'd dearly love to know why it runs perfectly well in the Companion. Does the Companion supply functionality that is missing in the app/hardware environment?
Sorry, just saw your reply.
The Android version on the tablet is 7.0, which is Nougat.
Perhaps the 1 GB of RAM is not enough to handle the processes, but I’d be surprised if that were the case.
Normally I wouldn’t mind if it was just this tablet that was misbehaving, but if I publish the app, I need to be sure that other devices will run it properly.