I would kill all the stuff in a mission, switch to a salvaging boat and as i start to move towards the wrecks, they just disappear. No cloaked ship appearing, no nothing. Just no wrecks anymore. I don’t do missions very often, i can’t tell if it’s every time. But so far it’s twice out of twice.
Wrecks only stay in space for ~ 2 hours before they despawn…
One of the problems though is this, lets say you complete a procedurely generated relic or other mission, or you have a problem and your capsule is killed outright? But you have a wreck, but because of warp restriction even inside High Sec System. You can’t scan detect or position. Now if you tagged your miscreant loot for later collection, usually that is okay. But that seems not right to suddenly have alot of materials suddenly verbotin. Its rather frustrating to see my D Scanner, which honestly is absolutely useless, suddenly fill up with tons of loot items. And I can not act upon nor fix any problems even it is my own.
Salvaging needs to be worked over, because its getting rather annoying to have these kind of issues, and you can salvage your own wrecks.