gspread: Gspread share function does not send email notifications anymore

Hi, i am using python 3.7.1 with gspread library version 3.1.0.

Until the 4th of October 2019, every time i shared a spreadsheet with a user, that user received an email notification. My share function is like this:

def share_spreadsheet_with_users(self, users_to_share_with):
    """

    :param users_to_share_with: the users with whom the spreadsheet will be shared
    :return:
    """
    for user in users_to_share_with:
        **self.spreadsheet.**share(user, perm_type='user', role='writer')

In the code above, the self.spreadsheet is a newly created spreadsheet and has type: gspread.Client

Ever since 4th October the user is only shared the spreadsheet (which can be seen in the google drive) but the user is NOT also notified on email. What could be the issue ?