Deeplinks using app URI handlers does not open the app

We have followed https://video2.skills-academy.com/en-us/windows/uwp/launch-resume/web-to-app-linking#register-to-handle-http-and-https-links-in-the-app-manifest to enable deep linking into our app. However, we can't seem to get it to work.

We've made sure

• to register to handle links in the app manifest
• to publish the windows-app-web-link json on our site

When clicking the link that should be linking to our app, nothing happens - we were expecting our app to be activated.

We're side-loading the app - to test the functionality before pushing to the Store.

Is there anything we're missing?