IFrame not able to access the camera or microphone.

Hi all,

We have a series of courses that have embedded Padlet iframes to allow for peer interaction. We'd like for users to be able to post videos. However, in some browsers, especially Chrome, the iframe does not prompt for camera/mic access and/or just stalls on the screen that says it's starting the camera/mic (see pic).

I verified that the iframe script is correct:

<iframe src="https://padlet.com/embed/tvncfcnwmikzcbqp" frameborder="0" allow="camera;microphone;geolocation"></iframe>

What am I missing here? Anyone run into this? Any ideas on additional script or browser settings that might help us at least provide customer support on the issue? Thanks.