CollabViewer Snapshot creates black Images in UE 4.25.4

I am using the CollabViewer for an architectural presentation. In UE 4.25.4 the snapshot function only creates black images. So I updated my project to 4.26.1. I can get now correct snapshots, but the button to end the snapshot mode does not exist - this is confusing for the customer. I have been searching all the blueprints, but this a little bit too advanced for me. Where is this small “exit button” (which is visible in 4.25.4) created or why is it gone? Its not in the Widged “Flash” - Can someone help?