IssueTracker

What steps will reproduce the problem?
1.  Use range.setValue() or range.setValues() inside a loop
2.  Note that all write operations occur only once the loop has completed, rather than in real-time.

What is the expected output? What do you see instead?

Range values used to update in real-time, a useful feature for providing the user a sense of progress as a Spreadsheet-bound script processes specific rows of data...as in a merge.  This used to be the way this function worked...

If possible, provide the code for a small sample script that reproduces the
issue:

function myFunction() {
  var ss = SpreadsheetApp.getActiveSpreadsheet();
  var sheet = ss.getSheets()[0];
  for (var i=0; i<100; i++) {
    Utilities.sleep(500);
    sheet.getRange(i+1, 1).setValue("This is a test " + i);
  }
}

Run this function and you will see that all write operations appear on the spreadsheet only once the loop has terminated.