Doesn't return all editors of my spreadsheet with the .getEditors function

Question

At my company we use Gsuite. We have a shared Drive with about ~80 colleagues. By default, every colleague is also editor in all the spreadsheets in that drive folder. So in one of those spreadsheet, I try to get an overview of all the colleagues. I'm using this code. It does work fine, but it just returns only ~60 colleagues or so. And I can't figure out why that is.

function getEditors()
{
  var sheet = SpreadsheetApp.getActiveSpreadsheet();
  var permissions = [];
  
  
  var  viewers = sheet.getEditors();
  
  Logger.log(viewers);
  
}

So far I can tell, everybody is an editor, just see the screenshot below.

And it's always the same colleagues that are missing. Hope somebody can help me with this!

Answer 1

With help from @a-burge I figured it out. Apparently I had to go to the settings in my shared Drive file, where I could see all the colleagues. There were a few who had 'Content manager' instead of 'Contributor' als a role. After changing this, it returned all the colleagues.