It happens on a dashboard grid with old filter feature as well. Appears to be another of many broken client-side grid issues. Appears to work if you can get the ExecuteBaq to do the aggregates server-side.
Like group then filter then refresh grid from grid actions. This seems to kick it into server-side mode (sometimes) you’ll notice it starts to ExcuteBaq request twice per group-expand.
Unfortunately, they spent resources to doing all this SQL and extra server trips instead of just making the client-side kendo grid built-in aggregation work as intended.