The short answer
You're not missing leadership ability. You're missing trust in your own mind as the thing that actually runs the room. The role didn't come with that trust built in — you have to build it yourself, from the inside, by acting from your judgment and watching it hold.
You were handed a title and a set of responsibilities, but nobody handed you the feeling that you belong in the chair. Research on leadership style shows that how a leader carries authority — the confidence, the tone, the decisiveness — shapes how others respond far more than the formal title does. When the inner story says 'I'm just covering this role,' it shows. People read it. The authority feels borrowed because, in your own mind, it still is.
Marcus Aurelius wrote that the mind, when it rules itself, does not bring fear or trouble upon itself. That's the key. The uncertainty you feel isn't coming from the job. It's coming from your own mind not yet trusting its own judgment. You keep looking outside — at the title, at others' reactions, at whether you 'seem' like a leader — for something only your judgment can give you. The identity takes hold when you stop waiting for it to arrive and start acting as if your read on a situation is worth following.
This week, pick one decision that is fully yours to make — something real, not trivial. Make the call from your own read, without asking for a vote or softening it into a suggestion. Then hold it. Watch what happens. You're not proving anything to anyone else. You're showing your own mind that it can lead without collapsing. Do that enough times, and the identity stops feeling like a costume.