Audio feedback and noise at screenshare

One of my team is hosting a meeting this week and running into issues when starting a screen share. Whenever a host or participant starts a to share a screen in a pod they start getting audio feedback of the presenter's voice or any other active mic. It sounds like an open mic picking up the audio feed of the meeting and broadcasting back. 

We have confirmed everyone in the meeting is muted. still happens

We tried enabling single speaker mode and it still happens

Is this something anyone else has encountered?

This is a meeting that has been used and reused for over a year. Not sure if this is a known issue with the latest upgrades.