Hollow Breakpoint in Visual Studio

I found all the breakpoints within the method BLE_Setup void are hollow when using the visual studio 22. Does anybody know why and Does anybody know how to debug into an asynchronous method?

setUpBackgroundObserver()
        {
            HKObserverQuery(heartRateQuantityType, null, (HKObserverQuery resultQuery, Action completion, NSError observerQueryerror) =>
            {


                FetchMostRecentData(heartRateQuantityType, (mostRecentQuantity, sampleQueryError) =>
                {
                    
                        BLE_SetUp();
                        
                });
            });


        }
private async void BLE_SetUp()
        {
            


            if (await BLE_Model.Instance.ScanDevices())
            {
                BLE_Model.Instance.selectDevices();
            }
            else
            {
                //scanning BLE devices failure, do nothing.
            }


        }