Oh my... It is still in the game
As you can clearly see oxygen isn't depleting while in radiated areas and anomalies - I think it gets bugged from picking them up from killed players, also this has happend with the wolf hearth - normal wolfs still attack me although i got it.
Please look into it.
Thanks for the reports @SadGuy.
We're already looking into the Matriarch Heart not working correctly when picked up from a killed player's lootbox.
I'll let the devs know that these two instances might be linked and hopefully it will help them identify a fix faster.
As we work on the fix, please keep the bug reports coming!