I can now confirm, there is a display? bug re. wrecks.
I had a battle with precursors recently. I knew they were there, so I brought some salvagers with me and ordered them to salvage the first two wrecks as soon as the enemy was defeated. I put some scouts where the wrecks were too, so I didn´t loose sight of them. However after some 10 days, when the salvager where about to reach the wrecks, they where nowhere to be seen on the system map (no restart of aurora either, played streight through).
The reason I think it is a display bug is, the salvagers still managed to salvage the wrecks I had ordered them to, even though I couldn´t see them anymore. Of course, there were more wrecks, but with those now being invisible, I can´t order the salvagers to salvage those (if I had known this, I had queud up those).
I have made a backup of the database with one wreck allready salvaged and the second some 5 days from finished