AFAIK there were several problems that the pax had. First, the app seems to work differently for IOS and Android, some of the guides were not familiar with one, or the other. Second, the app would inadvertently get shut off when pax were switching between photos and switching to another app, like text or emailing. Lastly, as you mentioned, some guests are not technology savvy enough to make the app work, change settings, make sure phone/ear-pods wee charged etc. It would cause a lot of annoyance to the other guests and the guide when someone would interrupt the presentation (constantly) that the could hear, the phone wasn't working, etc, and the guide would have to stop and fix the guest phone.
My sense it that the ShorEx crew has gotten tired of fixing/setting up guests phones, and of the myriad of complaints.
Me, I like it for the most part. The last time I used the app was in Ephesus, last fall on Splendor. The range was fairly good ans was the clarity. But I don't think the App system works any better than the guide supplied whisper boxes.
J