Google Apps Script fails to retrieve sheet by name

I'm having a very strange and persistent issue with Google Apps Script and getSheetByName().

I have a Google Apps Script script connected to a Google Sheets spreadsheet. The script is supposed to read data from a specific sheet (which I've named various things during my attempts: Tasks, PROJECTS, TEMP_PROJECTS, and finally DATA) and create events in my Google Calendar.

The problem is that even though I specify the sheet name correctly with SpreadsheetApp.getActiveSpreadsheet().getSheetByName("SHEET_NAME"), the execution log still says that it's finding a sheet called Sheet (which I assume is the default name of the first tab). As a result, the script can't find the correct data and doesn't create the events in the calendar.

What I've already tried (detailed list):

Checking the sheet name: I've checked and double-checked the name of the tab in my spreadsheet, making sure it matches exactly (including case) with the name passed to getSheetByName(). I've also tried different names.
Editing the code: I've checked that the sheet name is consistent throughout the script (both in getSheetByName() and in the log variables).
Audit log: I've used Logger.log() to track the name of the sheet searched for and the result of getSheetByName(). The log always shows that it searches for the correct name but finds Sheet.
Creating a new script: I've created a new Apps Script project and copied the code, but the problem persists.
Creating a new sheet: I've created a new worksheet and a new script, but the problem persists.
Renaming the tabs: I've tried renaming the tabs in various ways.
Restarting the browser: I've completely closed and restarted the browser.
Permissions Check: I have checked and re-granted permissions to the script to access the spreadsheet and calendar.
Simplified Script: I tried a very simple script to just search for the DATA sheet and log the result, but it keeps saying it found Sheet.
Google Account Sign Out and Back In: I have tried signing out and back in to my Google account.

Questions:

Are there any settings at the spreadsheet or account level that could affect how getSheetByName() works? Could there be a very persistent "caching" or syncing issue? If so, how could I fix it?

Solution

The problem is that even though I specify the sheet name correctly with SpreadsheetApp.getActiveSpreadsheet().getSheetByName("SHEET_NAME"), the execution log still says that it's finding a sheet called Sheet (which I assume is the default name of the first tab)

The default name of the first tab in a new spreadsheet is Sheet1 in the United States locale.

Chances are that your code looks like this:

  var sheet = ss.getSheetByName('x');
  Logger.log(sheet);

That means that you're not logging the sheet's name but a Sheet object. A sheet object is a JavaScript class that provides methods for accessing and manipulating the object's properties. When you blindly coerce it to a text string as in the above example, it will always render as Sheet. To log the sheet's name, use sheet.getName(), like this:

  const sheetName = 'x';
  const ss = SpreadsheetApp.getActive();
  const sheet = ss.getSheetByName(sheetName);
  if (sheet) {
    console.log(sheet.getName());
  } else {
    console.log(`Cannot find sheet ${sheetName}`);
  }

When no sheet by the name given is found in the spreadsheet, sheet.getName() returns null.

See Sheet.getName().