Sales and Return in LIS Reports

Dear Gurus,

Needed the expert opinion on the below process.

I post a 2 billing document $1000 each total $2000 and qty 10 each order total 20 unit.

after this when I run the sales report MC+E system shows the correct figure $2000 sale Qty 20.

I make one return of 5 units of value $500, return orerd > return delivery > credit memo.

I run the report MC+A and MC+I which show the correct data like

Incoming return $500 return qty 5

but after this when I run sales report MC+E system shows the sale $2000 and qty 20 units, it cant reduce the sales value by $500 and units by 5 .

Just want to confirm that is it a standard behavior of LIS reports. ??

Looking for gurus feedback.