Problems with sharing content on Webex app

When hosting a webinar with Webex, I found it impossible to share my screen. I am using a MacBook Pro 14". Apple M3 Max; The OS is 14.1.2. The app repeatedly asks to "Allow Webex to share your Content" and pointed by default to Open System Preferences. Even after doing so and restarting, the thing kept happening like an unending loop. My previous MacBook 13" had no problems, but I was using OS Monterey. I have gone through every item in the Privacy & Security section in the System Preferences and found nothing else to click on or off. I wonder if anybody else has encountered this problem with Webex or similar problems with other applications such as Zoom. Thanks.