KevinTheJedi Just to add another confirmation, this modification worked for me when using a shared mailbox. However, I did log into the shared mailbox directly (yes, I know - not best practice but it works), so I'm not sure this provides any additional information for confirmation of a fix šļø
Thanks for the modification! I suspect a lot of people will have expired client secrets around now given it's just over 2 years since the plugin was released!