Background fetch not executing

Question

iOS is not executing PerformFetch.

I've put the app in the background and just left the device. It's been three days and still PerformFetch is not executed. I know this because I'm using event tracking in MS App Center.

public async override void PerformFetch(UIApplication application, Action<UIBackgroundFetchResult> completionHandler)
{         
        Analytics.TrackEvent($"{DateTime.UtcNow} Background fetch started");

        if (App.IsSyncInProgress)
        {
            Analytics.TrackEvent($"{DateTime.UtcNow} Background fetch failed - Sync in progress");
            completionHandler(UIBackgroundFetchResult.Failed);
        }

        App.IsSyncInProgress = true;

        var loginService = App.IOCContainer.Get<ILoginService>();
        var tokenStorageService = App.IOCContainer.Get<ITokenStorage>();
        var syncService = App.IOCContainer.Get<ISyncService>();
        var userRepo = App.IOCContainer.Get<IUserRepository>();
        var sarService = App.IOCContainer.Get<ISuspiciousActivityReportService>();

        bool? result = null;

        try
        {
            if (await loginService.IsUserAuthorised())
            {
                var user = await userRepo.FetchUser();
                var bearerToken = tokenStorageService.FetchBearerToken(user.UserPrincipalName);

                if (bearerToken != null)
                {
                    result = await syncService.SyncData(bearerToken);
                    Analytics.TrackEvent($"{DateTime.UtcNow} - SyncData result: {result}");

                    result = await sarService.RetrySubmitOutstandingSuspiciousActivityReports(bearerToken);
                    Analytics.TrackEvent($"{DateTime.UtcNow} - RetrySubmitOutstandingSuspiciousActivityReports result: {result}");
                }
                else
                {
                    Analytics.TrackEvent($"{DateTime.UtcNow} - Background fetch silently failed, bearerToken is null");
                }
            }
        }
        catch (System.Net.WebException webEx)
        {
            Analytics.TrackEvent($"{DateTime.UtcNow} - Background fetch failed due to Exception: {webEx.Message}");
            completionHandler(UIBackgroundFetchResult.Failed);
        }
        catch (System.Net.Http.HttpRequestException httpEx)
        {
            Analytics.TrackEvent($"{DateTime.UtcNow} - Background fetch failed due to Exception: {httpEx.Message}");
            completionHandler(UIBackgroundFetchResult.Failed);
        }
        catch (Exception ex)
        {
            Analytics.TrackEvent($"{DateTime.UtcNow} - Background fetch failed due to Exception: {ex.Message}");
            completionHandler(UIBackgroundFetchResult.Failed);
        }
        finally
        {
            App.IsSyncInProgress = false;
        }

        var response = result == null ? UIBackgroundFetchResult.Failed : result.Value ? UIBackgroundFetchResult.NewData : UIBackgroundFetchResult.NoData;

        Analytics.TrackEvent($"Background fetch finished {DateTime.UtcNow} - result: {result}");

        //Console.WriteLine($"PeformFetch - Completed: {result}");

        // Inform system of fetch results
        completionHandler(response);
    }

I know that iOS determines when to execute the background fetch but really?! Three days?!

Pretty sure all my code is correct because I can simulate a Background Fetch in the Simulator successfully, but get nothing when on a real device.

I've checked through the device logs and notice that iOS is actually determining that the background fetch should not run

Jan  8 10:09:28 my-iPad dasd(DuetActivitySchedulerDaemon)[105] <Notice>: com.apple.fetch.com.imptob.ituk.sara:F276C2:[
    {name: ApplicationPolicy, policyWeight: 50.000, response: {Decision: Must Not Proceed, Score: 0.00}}
 ], FinalDecision: Must Not Proceed}

Jan  8 10:10:09 my-iPad dasd(DuetActivitySchedulerDaemon)[105] <Notice>: Submitted Activity: com.apple.fetch.com.imptob.ituk.sara:20D953 <private>

Jan  8 10:10:09 my-iPad dasd(DuetActivitySchedulerDaemon)[105] <Notice>: CANCELED: com.apple.fetch.com.imptob.ituk.sara:F276C2 <private>!

Jan  8 10:10:20 my-iPad dasd(DuetActivitySchedulerDaemon)[105] <Notice>: com.apple.fetch.com.imptob.ituk.sara:20D953:[
        {name: ApplicationPolicy, policyWeight: 50.000, response: {Decision: Must Not Proceed, Score: 0.00}}
     ], FinalDecision: Must Not Proceed}

Jan  8 10:12:07 my-iPad assertiond[67] <Notice>: [sara.ios:666] pid_shutdown_sockets(2) success

Jan  8 10:12:09 my-iPad dasd(DuetActivitySchedulerDaemon)[105] <Notice>: com.apple.fetch.com.imptob.ituk.sara:20D953:[
    {name: ApplicationPolicy, policyWeight: 50.000, response: {Decision: Must Not Proceed, Score: 0.00}}
 ], FinalDecision: Must Not Proceed}

Previous apps I've developed have performed the background fetch without issue although those apps were used quite regularly.

Does this seem normal?