function as a filter criterion works in some reports and not in others

function as a filter criterion works in some reports and not in others

In several reports I use the same filter that is the value returned by a function.It worked fine until recently.
Suddenly now in some reports it works and in others the criteria of the type:

"thisapp.MyFunction ()"

has been replaced by

"<FUNCTION ()> "

and does not let me change it.I have already contacted the technical service and they have been checking it for days but at the moment no solution. If anyone has any ideas, help is appreciated.