Is there some kind of weird lopsided loot allocation system in parties?

So this is going to be entirely anecdotal, as I have no properly recorded data, but it seems to me that the game doesn't allocate loot remotely evenly between party members.

Last league, my wife generally had more time to play than I did and generally had progressed further, so we often ended up with her running the maps, while I just tagged along. Whenever this happened, it seemed that I got the lion's share of the decent drops.

This league our timetables are reversed, and generally I've been running maps with my wife tagging along. And the drop situation has reversed; I'm trying to farm essences at the moment, and in the 30 maps we just ran, not 1 of the top essences dropped for me. I think I received 3 essences in total, all junk tier; in the rest of the cases I got literally nothing out of it... every single one got allocated to her.

It's got to the point where my motivation to play is now entirely morbid curiosity... how long a streak of maps can I run in a row without receiving any essences? So... is this literally just absurdly weird luck, or is there some kind of mechanism to push drops towards whoever doesn't own the map?