I’m running into a very similar issue as the following topic that appears to be resolved via DMs by @elisa.zoom : Zoom Scheduler Events Using Zoom API (created in Jan 2025).
We have created an automation that attempts to retrieve meetings booked in our Zoom Scheduler page using the GET scheduler/events API. The S2S OAuth app is configured with the correct scopes and the API can be accessed and returns a bearer token, but all calls return an empty items[] array. I can see the scheduled events from the Zoom Scheduler UI and I am able to use the GET meetings/{meetingid} API to return meeting information for the meeting created from the scheduler.