I have a functioning app script to add events to a Google Calendar. Calendar events are correctly created in the calendar, with guest if applicable. Logs show the guest email is being properly recorded. This is my script:

function addEventsToCalendar(e) {
  if (e.range.columnStart != 11 || e.range.getValue() == "" || e.range.offset(0, -10).getValue() == "") return;
  const rData = e.source.getActiveSheet().getRange(e.range.rowStart, 1, 1, 15).getValues();
  const calendarId = 'insertcalenderid'; // Replace with your calendar ID
  const calendar = CalendarApp.getCalendarById(calendarId);
  let date2 = rData[0][1];
  let request = rData[0][2];//psr or clin
  let loc = rData[0][3];//event location
  let starttime = rData[0][4]; //start time
  let endtime = rData[0][5];  //end time
  let floatName = rData[0][7];
  let status = rData[0][9];
  let guestEmail = rData[0][12];
  var title = floatName; //event title
  var title2 = "Not assigned"

  if (date2 !== '') {
    var startdate1 = Utilities.formatDate(new Date(date2), SpreadsheetApp.getActive().getSpreadsheetTimeZone(), "MM/dd/yyyy");
    var enddate1 = Utilities.formatDate(new Date(date2), SpreadsheetApp.getActive().getSpreadsheetTimeZone(), "MM/dd/yyyy");
    var starttime1 = Utilities.formatDate(new Date(starttime), SpreadsheetApp.getActive().getSpreadsheetTimeZone(), "hh:mm a");
    var endtime1 = Utilities.formatDate(new Date(endtime), SpreadsheetApp.getActive().getSpreadsheetTimeZone(), "hh:mm a");

    // Log values to debug
    Logger.log(`Date: ${date2}, Start Time: ${starttime}, End Time: ${endtime}, Title: ${title}, Guest Email: ${guestEmail}, Status: ${status}`);

    // Get start date, start time, end date and end time and reformat to correct date and time format for calendar


    // Combine date and time for calendar event
    var startDatetime = new Date(`${startdate1} ${starttime1}`);
    var endDatetime = new Date(`${enddate1} ${endtime1}`);

    Logger.log(`Start Datetime: ${startDatetime}, End Datetime: ${endDatetime}`);

    if (rData[0][0] !== "" && status !== 'X') {
      let event;
      let eventID; // Declare eventID in the correct scope
      if (guestEmail !== "") {
        Logger.log(`Creating event with title: ${title}`);
        event = calendar.createEvent(title, startDatetime, endDatetime, {
          location: loc,
          color: 5,
          guests: guestEmail,
          sendInvites: true
        });
      } else {
        Logger.log(`Creating event with title: ${title2}`);
        event = calendar.createEvent(title2, startDatetime, endDatetime, {
          location: loc,
          color: 5
        });
      }
      Logger.log(guestEmail);
      // Capture the event ID and remove the @google.com part
      eventID = event.getId().split('@')[0];
      Logger.log(`Event ID: ${eventID}`);

      // Write the event ID to column N (14th column, since columns are 0-indexed)
      const currentCell = e.source.getActiveSheet().getRange(e.range.rowStart, 15);
      currentCell.setValue(eventID);
    }
  }
}

Everything is working properly, except for no invitation is sent to the email provided. The log shows the correct email. I have tried:

hard-coding the email,
using different emails,
using a different personal account not in my organization to run the script,
using different calendars,
setting calendar permissions to full management permissions,
ensuring that calendar is shown/permission is given to view all details,
running the script through ai,
googling the problem (including stackoverflow)

all to no avail.
I was expecting an email invitation to be sent.

Does anyone have any insight as to why this script would not be sending out the invite?