Rowsol wrote:It turns out there's just a delay until you can pick a card. I can't say I'm a fan.
And can I get a clarification on what the assassin mod does?
I'll add a cvar to disable the buffer next version. It's there to prevent people from accidentally picking cards when loading a save, as I've watched too many streamers struggle with that for some reason.
The Assassin will spawn a monster near you to come after you at a random point in time, and has a few buffs. Next version you'll be able to find out what this and every other card does in detail

I'm not using any mods and it just happens sometimes.
I've tried in vanilla with a few maps and couldn't get it to happen. Probably goes without saying but did you use any cheats? Or any save games?