First, thank you GlennD for responding with a good amount of detail about the issue and confirming that something on your backend has changed that "broke" the app. I hope you can now shed some light on other aspects of this issue...
When you say "Generally low usage", are you talking a dozen users, a hundred users, a thousand users, or more?
I ask because I depend on the app to manage my clients when I am on the road, which is a lot and I would think many other customer's of yours does the same thing.
So, I am having a hard time understanding how can your company discontinue an app without any notice (even in the app) and not have an alternative solution for our mobile phones to use after the sunset date?
This is not a situation of a customer asking for continuous changes to your app, even though they only paid ONCE for it - We are paying your company on a MONTHLY/YEARLY basis, so I fail to understand why "the effort required to release a new version" is even a problem because we are paying for continuous service/development.
Please reconsider your company's decision to no longer support android devices, otherwise I will be changing my monthly payments to another company.