Default aggregation association doesn't work on S4H 2020 with new syntax

Hello.

I am trying to add a grouping for my list report with some statistics (sum, max and other).

But on the new syntax, nothing happens: on new syntax we can't use annotation "Default Aggregation" cds view perceived as a transaction and we can't expose this view, while on the old one, everything works fine. Could you tell me what the problem might be? And how can grouping be done with the new syntax?