We faced the same challenge - we have multiple individuals who can create webinars and are Marketo users. However, when searching for Zoom webinars in Marketo, we saw webinars created by only one individual. We fixed this issue by asking our Zoom administrator to add the email addresses of the additional webinar users to a section of the Zoom-Marketo integration (this screen is in the Zoom user interface). This configuration is controlled by Zoom, not Marketo. You can have multiple users create webinars in Zoom and pull them into Marketo using the same API.
In our case (this may have been random) but we needed to re-authorize Zoom in Marketo for the webinars to resume pulling in after we added the additional users. Hope this helps!
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