If this aircraft was cleared for only one orbit
Does not sounds right . You do not need to go to a special area to make a single 360.
The key to this is in the pre de briefing details. I have been involved in airshows organisations and the details of every and each flight presentation or demo flight is discussed and agreed upon in a large briefing between actual Pilots , Show organisers and ATC each day . How long this particular demo was planned for is therefore recorded somewhere.
Wait a bit more for the details.
Again , this "radio silence "as you call it , is not a cause of this accident