Date functions used in report criteria lost on re-edit

Date functions used in report criteria lost on re-edit

I have a number of reports set up using date functions such as 

'Added_Time' ... Before ... today.subDay(7)

to find records that are over a week old.

These can be created OK, and work fine. However, when I go to edit the report criteria again, "today.subDay(7)" is always turned into just "subDay". In order to save the correct criteria, I have to retype " today.subDay(7)" into the text box before save.

The same happens for other functions e.g. addDay, subMonth, etc.

I've got this on a lots of reports, and often with more than one date criterion applied per report. So editing report criteria becomes more of a time-consuming and error-fraught task than it needs to be.

Please could you enable maintenance of these  these time-based  criteria, even when the criteria for the report are opened up for editing again?

Thanks.