If you're unable to update to OS 12, it is possible that uninstalling and reinstalling the app would help out, but I'm hesitant to suggest that since you're unable to find the app in the App Store. Check to see if this direct link to the app works out, and if so, then go forth with the uninstall/reinstall.
ecobee on the App Store I have had times where I could not connect with my thermostat via the iPhone app, but I could not connect with other apps at my home at that same time, indicating that my very poor internet connection was temporarily down. I can find no fault with the ecobee app, and I … apps not downloading from appstore 2019 iOS 12, iOS 11 Dec 28, 2017 Why is the app store not updating/downloa… - Apple Community Mar 21, 2016
Etsy App for iPhone Not Working - Welcome to the Etsy
You can still update your iPhone or iPad apps in the App store. You just have to know where to look. Jason Cipriani. June 4, 2020 6:00 a.m. PT. Listen - 01:32. Nov 20, 2019 · UI changes to the App Store aside, the problem of apps not updating when they’re supposed to is an entirely different problem. A problem with no clear solution at present. Users have tried everything from force-quitting the App Store app to rebooting the iPhone, to signing in and out of Apple services again.
APPLE APP STORE NOT WORKING FIXES FOR IPHONE. With a little effort, you will have your App Store rebooted and functioning in no time. The following solutions are applicable to Apple iPads, iPods, iPhones. CLOSE THE APP STORE. This is an often overlooked option, but sometimes simply force-quitting the App Store is the quickest fix for this problem.
How to fix App Store not working on iPhone Jun 20, 2020 How to fix an iPhone XR not connecting to App Store Oct 29, 2018 6 Tips to Fix Safari Not Working on iPhone/iPad- Dr.Fone Jul 17, 2020