Original Post — Direct link

If you run a Thieves' Trinkets or Currency grand heist and click on the trinket slot box when you already have a trinket equipped, it will delete the one that you have.

Seems like the patch made it so the trinket slot box at the end of the grand heists show up again after already unlocking it, so watch out.

External link →
26 days ago - /u/RhysGGG - Direct link

You probably ran the Grand Heist on a character who had not unlocked the Trinket slot.

Clicking the box literally doesn't do anything other than set a flag. That's it. The box isn't even clickable if you've already clicked it and unlocked the slot. And nothing has changed with this since league start.