Well this is the problem. Jumping will merely drop a heroic item and it does not count for the tally that way. You need to use leftclick (or whatever your attack button is on console) to place the treasure within the radius, for it to count.
For small treasures to count you need to put them in the quickbar, and place them from there like any placable that is crafted at artisans bench.
ps. Ive also recently discovered that one of my heroic treasures that I thought vanished, did indeed fall through the building blocks. Yesterday I moved my treasures to a new location, so there might be more to come…