Meeting Participants Unable to See Eachother

I have set up a Zoom integration through a scheduling program for the company I work for. We have been having a lot of issues with Zoom meetings - most notably, the admin and client will join the meeting but neither will be able to hear or see each other, it appears as if they are in the Zoom room alone. The admins join the meetings directly from the Zoom site under the profile that is integrated with the scheduling app and the clients join the meeting from the Zoom link that the scheduling app sends out in the confirmation email. Just wondering if anyone else has had this issue and knows how to fix it since, after talking to the scheduling app's support team, it doesn't appear to be an issue on their end.

Thanks,

Sophie