After some more playing, it doesn't seem possible to sort by multiple columns sad
It was probably luck that resulted in landmarks appearing as being sorted by multiple columns.

Another nice feature would be to group landmarks by type. Each group could be collapsed or expanded as needed.

Your suggestion sounds like a good idea. In effect, you become the owner of the loot if you have flagged the target and it is your primary target.

I'm always a little wary of over complicating gaming mechanics, but this would seem a straightforward change. I imagine the agents abusing the current loot system wouldn't like this change, but it does seem fairer.

A simpler solution maybe to reduce the time that a target remains flagged. If it was reduced to some thing like 10 seconds, then targets that are not primaries are likely to drop their flag.

I've just had a quick play, and it seems that it's possible to sort by multiple columns. There doesn't seem to be any indicator tho.

When a lot is happening the landmark window can get a bit crazy.:D

One way to help organise targets would be the ability to sort the table by more than one variable. For example, you may want to sort by type first, then by distance. In many applications this is achieved by holding the "Ctrl" key then clicking on the column header of each of the columns you want to sort.