BGContinuedProcessingTask does not respect fractionCompleted to keep alive

I posted here https://developer.apple.com/forums/thread/805554?page=1#867766022 but posting again for visibility (and let me know how I can file a bug)

There was a response in that thread that said you could use the childProgress system to help updating progresses to keep the backgroundTask alive.

What I've found is that using childProgresses results in more terminations than if you just updated the progress directly.

Here is my setups to test this

1. A BGContinuedProcessingTask that uses URLSessions to upload, and registers the task.progress with the Urlsession Progress
2. Same, but the task.progress gets updated via a UrlSession Callback

The second is MUCH more stable out in the field in cellular settings, the first fails extremely frequently.

My suspicion is that in the documentation here https://developer.apple.com/documentation/foundation/progress#Reporting-Progress-for-Multiple-Operations

it explicitly states

The completedUnitCount property for a containing progress object only updates when the suboperation is 100% complete. The fractionCompleted property for a containing progress object updates continuously as work progresses for all suboperations.

I wonder if BGContinuedProcessingTask is only looking at completedUnitCount for progress, and not fractionCompleted?

In either case, I would love to use the childProgresses because there are bugs with retries by updating the progress manually, so would love some help resolving this, Thanks!