Can't use Push-To-Talk in Steam's voice chat while in Delta Force

[Eazzych]

Title. It's kinda weird, to be honest. In any other game, voice chat works flawlessly. In DF, Steam's push-to-talk doesn't work, only open mic works. Why is that? Is that a bug, or intentional? PTT only starts working when I tab out of the game, that never happened before in any other game.


Just in case: I'm talking SPECIFICALLY about steam's built-in voice chat. Not ingame VC, not discord VC - just Steam.