Group Reporting Data Monitor: Due to the latest upgrade, no ledger could be assigned to this version

Hi Experts,

we are working on a group reporting ON PREMISE 2020, SP 01 (02/2021) FP.

As suggested by SAP, we installed Best Practices as a starting point. After the installation, I checked the Data Monitor and everything was working correctly. I created a company (correctly I would say) and the Data Monitor was still working. After that, I created the Consolidation Group, as per the manual, and loaded the mapping between GL Account and FS Item, then I tried to access the Data Monitor and it returned the following error message:

"Due to the latest upgrade, no ledger could be assigned to this version.The master data is incorrect and therefore you can’t use this version.Please contact SAP to solve this issue."

We used all the predelivedered Master Data (Consolidation Ledger, Version, Consolidated Chart of Account).

Has anyone faced this issue before?

Thank you for your help,

Giulia