Bug during screen sharing on Bigbluebutton 2.7.4

[Sergey Chubenko]

Hello everyone, dear colleagues! I ran into an unusual problem. Bigbluebutton 2.7.4 is installed on the server, I found an error with the screen sharing. From the presenter's side, the demonstration of the desktop and individual tabs works fine. But on the user's side, there is a simple blue screen, or a screen with 3 dots. A similar problem is observed if another user starts sharing screens as a presenter, other users see a blue screen.At the same time, the recording of the webinar shows that the presenter shares the screen with the user. I thought at first that the problem was in kurento, but port 8888 is open. Can you tell me how to fix this bug?