Export sleep data in HealthKit from specific App only?

Unfortunately the Sleep++ export (via mail) function is not working for me on iOS 14.

That’s why I want to try to export all its sleep data using a shortcut instead. I can get sleep data for all Apps at once, but as soon as I add an additional filter (beside the default start date), source (Sleep++, or any other App that writes sleep data to HealthKit), the shortcut no longer returns any entries…

How can I fix this? (Or any other way to get my data for Sleep++ only?)