This is the actual cause for the issue. The delay is a workaround.
this is documented I just did not understand it:
"Calls to the API only prompt when the application state is UIApplicationStateActive." (https://developer.apple.com/documentation/apptrackingtransparency/attrackingmanager/3547037-requesttrackingauthorization)
AgustAcc
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The delay is a workaround. The actual issue is that the request has to be called when the application state is UIApplicationStateActive.
This is documented but the significance can be hard to understand:
"Calls to the API only prompt when the application state is UIApplicationStateActive." (https://developer.apple.com/documentation/apptrackingtransparency/attrackingmanager/3547037-requesttrackingauthorization)
so make the call in "applicationDidBecomeActive"and all will be good.