Process Quality Tasks - App ID: F3250 - No Task Processors available?

Hello,

I have a problem with the Fiori App "Process Quality Tasks" - App ID: F3250: being on S/4Hana 2021. The Task Processor doesn't take any input and the search input doesn't return any results even when using wildcard *. Manually entering a username or a BP Id results in:

Yet i know for fact that 144 exists as business partner. So how can i make them Task Processors?

Here's my URL in case any parameters are relevant here: https://<hostefqdn>/sap/bc/ui2/flp?sap-client=300&sap-language=EN#QualityTask-process?DefectInternalID=%252400001000001&QualityTaskOrigin=01⪯ferredMode=create&sap-app-origin-hint=&sap-xapp-state=TAS1WLB5H84P774UA5KTQRHN9NYRLBQFXN8V1YHR1&/C_QualityTaskProcess(QualityTaskInternalId='%252400001000071',DraftUUID=guid'005056b0-0973-1edc-9ed7-be3ae3a320ec',IsActiveEntity=false)/?sap-iapp-state--history=TASLKSV8NRZO7VDVS82YGCNGWT8QG4A1H8UFXF97B&sap-iapp-state-C_QualityTaskProcess=ASQVVBPEABMI1ONJ6KO4S4SXONU6DWSWE8XGPYYT

I've found this app "Manage Workflows for Quality Task Processing" (F4977) and though that might be related .. but even after activating that app and enabling the WS via SPRO and it started to show up in the APP it didn't result in any changes regarding my task processing issue.

Any pointers here would be appreciated.

regards

Christian