There is a strange problem with old Nexus 7 devices (Android v5.1) which show fail messages but not success messages. This is even more confusing in that the success is not a full success as nothing is logged to my log file but it can connect to the php file.
Testing on a Samsung S6 and the test sandbox environment is fine.
Arriving this week is a Mac Mini so testing can begin on Apple products. Hopefully the bug is confined to old Android versions.
Regardless, I’ve posted online to a forum where i hope I can get some fresh eyes on the problem.