SensorKit - didFetchResult never get called.

We tried to fetch the recorded PPG data using SensorKit with the following code, however the didFetchResult callback method is never called.

let ppgReader = SRSensorReader(sensor: .photoplethysmogram)
let request = SRFetchRequest()
let nowDate = Date()
let toDate   = nowDate.addingTimeInterval(-25 * 60 * 60)
let fromDate = toDate.addingTimeInterval(-24 * 60 * 60)
request.from = SRAbsoluteTime.fromCFAbsoluteTime(_cf: fromDate.timeIntervalSinceReferenceDate)
request.to   = SRAbsoluteTime.fromCFAbsoluteTime(_cf: toDate.timeIntervalSinceReferenceDate)
ppgReader.delegate = self;
ppgReader.fetch(request)

The delegate called the didComplete successfully:

func sensorReader(_ reader: SRSensorReader, didCompleteFetch fetchRequest: SRFetchRequest)

But never called the didFetchResult

func sensorReader(_ reader: SRSensorReader, fetching fetchRequest: SRFetchRequest, didFetchResult result: SRFetchResult<AnyObject>) -> Bool

Any ideas why ? (I am wearing the watch for couple days and ensure it has the data for the time period I am querying)

One thing I notice is when Apple granted us the entitlement, it uses Uppercase for ECG and PPG, however the document use Lowercases in the plist https://developer.apple.com/documentation/sensorkit/srsensor/photoplethysmogram

Dose it matter ?

SensorKit - didFetchResult never get called.
 
 
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