[Q]

Well I tested this in the simulator and cannot confirm it. The hit chance of the weapon platforms on the planet was lower than 99% even in the presence of 15 fighters all with combat sensors. Even more the hit chance decreased like it should with the target distance.
Second I tested also satellite Groups with ECM and combat sensors. Here too everything seems to work as it should.
It is just fighter Groups that have the bug. And the bigger the fighter group the bigger is the combined effect of the ECM/combat sensors (see corresponding topic).