Clicking Link opens App on some devices and not others.

We have a situation where our app in the app store is configured to open the app when a link is clicked on (such as in an email) however all of the devices of one of our developer's does not open the app when the link is clicked on.

We presume that there is a setting on one of his devices that has disabled the feature, and that this setting has been copied via iCloud to all of his devices.

We had thought that this was an operating system bug however we have established that other developers click on the links in any of their devices (no matter the OS version, from 12.x to 14.6) and the app opens.

Can anyone solve this issue, that is, what setting can disable clicking on links to open an app, and hence what should be enabled to resolve the issue.

We can't let our latest app release pass QA without resolving this, so if anyone has any suggestions, however remote, please suggest them, as every day we lose is expensive.

Kind regards.

Clicking Link opens App on some devices and not others.
 
 
Q