I have finally tracked down the problem with wrecks. There are still there and they aren't moving and they can be picked up by active sensors. However, in certain circumstances the code to check those sensors won't run so they will never be detected.
To avoid checking every sensor on every ship in every system during every sub-pulse, Aurora keeps a database table called SensorChecks. This table contains a list of systems where more than one race is present or where civilians are present. This table is updated every time a ship transits a jump point or a colony is created. During the sensor phase, the sensor code only runs for systems in this table (as there is nothing in the other systems to detect). However, when determining the systems that should appear on this table, wrecks were never considered. So if you have a system with wrecks but no colonies or ships from other races, you won't be able to detect them. As soon as there is a second race in the system, the wrecks will detectable again because the sensor code will run for that system. They will stay detectable until the next 5-day increment when a piece of code runs that remove entries on the SensorChecks table where only one race (and no civilians) is present.
I'll update the code for version 4.1 so that wrecks are a reason for a system to be added to the table.
Steve
