Not receiving "In-meeting chat message received" events

Hello,

I’m having troubles receiving “In-meeting chat message received” events.

My account plan is Zoom One Pro
I’m working on the application that should be able to receive chat messages sent by the users during their Zoom meetings.
“In-meeting chat message received” event is selected among the other events in “Event Subscriptions” app section.
My Application has “View current user’s team chat messages /chat_message:read” scope.
DLP is enabled by the support team ( got from them …Please be advised that we have enabled the in-meeting chat DLP integration feature on your account…).
“Enable advanced chat encryption” toggle is off.
Webhook URL is verified, and I am able to receive other events, such as "meeting started/ended, participant joined/left meeting), e.g. I’m getting requests such as

{"event":"meeting.started","payload":{"account_id":"....

However, I am not seeing any events when person writes something in the Meeting Chat window

Could you please help me understand what I’m doing wrong/missing?

Thank you very much