Appointments don't show up in Gcal after setting up google API

Hey,

I have been using the appointments+ plugin for a while now, I had it setup perfectly so it also synced with my google calendar.
However, since I am abandoning my google g-suite account, I had to setup my appointments plugin to sync with the calendar of a different gmail account.
I follow the instructions to setup the API, I can even select which calendar it has to sync with, but the appointments never show up in my calendar.

I have set this up before without any problem so I'm quiet sure I did something wrong.
Except I can't see it. I have also searched the forum and used google but can't really find the answer.

Thanks for your help,

kind regards,

Sven