when you ask someone a question and they just completely ignore you like you didn't even speak

I ask my coworker if she wants coffee. She stares at her screen. I ask again—nothing. So I pour her a cup anyway, set it next to her keyboard, and leave. Twenty minutes later she emails me: "Why is there a cup here?" Apparently I'd been talking to her the entire time while she was on mute during a Zoom call with her camera off, which means she was actually just napping.