This affects when several elements can be superposed like in geography, level 6.
If we place Russia then Estonia, we can select Estonia and move it by clicking on it.
However, once we select Russian and drop it back at its place (or if we place it after), even if we click on Estonia, it will be Russia selected.

It's probably a z-order issue, with the first/last element selected.
Depending on how much levels/activities it can affect, maybe the solution is to add a z-order in the dataset for these specific elements.