I have a web app integrated with the iOS Square POS app. My web callback URL is not being called. The app supports an event that occurs annually. It worked successfully last year and the the year before. I’m out of ideas for troubleshooting. I know that my URL works as expected when I call it manually, and I know the iOS POS transactions are successful. I know that the callback URL on the setup page matches the callback url in my javascript call to the iOS POS app. The format of my url is
https://mywebsite.azurewebsites.net/PurchaseDucks/POSCallback
“mywebsite” is my actual website name.
Any tips for next steps to debug my issue?
Were there any changes to made to your application and is the Square app up to date? 
For testing I’m pointing to a test version of the app instead of the production version. But other than that, no changes. I verified that the callback URL on the setup page matches the one in my javascript that launches the square app. I deleted and reloaded the Square app on my iPad. Many thanks.
Can you verify that the square servers are making the callback?