Today I borrowed an iPhone Xs from my Son who runs a Telephone Store here in Victoria, BC. It has a newer version of iPhone software version installed (13.3.1). I found that almost immediately when I arrived on site of the missing Adventure Lab it registered on the iPhone Xs and asked for the answer to the on-site question be answered. I did that and the site was recognized as complete and it asked me to rate the Adventure Cache and add my comments. My submission was accepted and the cache count went up by one accordingly. Back at the Telephone Store we discussed this. The information I received from the experts is that my Model of iPhone 6 plus running Software version 12.4.5 is no longer being updated by Apple because of the phones age. It seems the solution to my problem is to buy a newer iPhone which can run the newer software if I wish to complete Adventure Caches of 5 or more sites.