get cells in range and paste as values Apps script

I have a range A2:Z5000 that i am trying to paste as values in the same exact range (turn formulas into fixed values)

In range A2 i have a ImportData formula fetching data from a csv file.

My script goes like:

var sheet = SpreadsheetApp.getActive().getSheetByName('MYSQLimport');
sheet.getRange("A2:Z5000").copyTo(sheet.getRange("A2:Z5000"), {contentsOnly:true});

but it erases the content instead of setting it as values…