Thank you for all your replies. This is crazy though, it should be fixed. With some objects it is crucial that the objects vanish properly. Why not do a viewer update at least when the person moves back into the range of those items/the items are within draw distance?
This bug practically makes it impossible to script objects which appear and disappear frequently. I tried so many things, I even dropped the llDie command completely and made them transparent, scaled them down, moved them to a far off position of the region and made them temp. I had a timer do all that repeatedly for a higher chance to actually have all viewers being updated until the garbage collector actually removes those items server-side. Still no luck. They visually remain in place for people that were in the region at the time but not within draw distance as if nothing had happened.
I can't think of any solution/workaround for this problem on my part... Very annoying.