[Appointments+] Appointments+ Settings ->Google Calendar Tab… Empty

I’ve just updated to version 2.4.0. Now in settings, Google Calendar Tab, the page is blank. Tested on Mac 10.12.6, Chrome Version 67.0.3396.99 & FireFox 60.0.2 & Safari 11.1.1. Any thoughts? I’ve opened the WPMUDEV support lock on my site.