Sorry about this problem.
This happens when we don't have ground level data from an airport.
This when combined with "Move Planes" in Settings is causing the problem.
The Move Planes (or Estimate Positions on the website) is designed to calculate positions based upon last know position, heading and speed.
It is designed to fill gaps between data updates.
When coming in to land planes can disappear from range of our receivers as is happening at FCO I think.
Our estimations can then project their position inaccurately. After a while they will timeout and disappear from our maps.
We are looking for a data feed or a location for our own equipment near FCO.
Please let us know if you know anyone that can help with this.