There is not enough good OGN receivers in competition area, that is clear.. That's why tracking does not work. Even one good receiver in Ostrow would make a huge difference.
Ensuring a good receiver coverage is one of the items that require significant lead times. OGN experts developed a long range receiver setup which is available at less than 200€ (e.g. he
http://ognrange.onglide.com/#EDOV,ma...f f,circles;), but it takes some efforts and collaboration from other clubs to distribute these throughout the countryside.
It should be noted that some pilots choose to turn their flarm off while flying.
During the last IGC meeting, a year 1 proposal was adopted to separate collision avoidance like FLARM from tracking hardware. This is aimed towards preventing pilots from switching off their FLARM units in order to hide themselves in tracking. Separate OGN trackers will have to be used. They are in the works and start to be available at reasonable costs (some were built in Poland already).
The trackers that were used at Benalla WGC unfortunately proved to be completely unreliable in European networks.