I work 2 days a week as support staff at a 6th form college, and I've been doing this for around 3 months now. I'm timetabled to be in certain rooms at fixed times during the 2 days.
On several occasions now I've had other teachers burst in whilst I'm doing my interventions, trying to turf me out because they need a room, "Are you meant to be in this room?" "Are you actually timetabled here?"
I've just had one burst in "Are you actually working in here?"
No, I thought I'd just sit in some random room for the sake of it.
Each time I tell them very clearly, yes, I am timetabled here.
I find it undermining and they wouldn't do it to 'proper' teachers. It's also rude of them to interrupt my interventions with students.
They seem to think because I'm 'just' support staff then I'm just grabbing random rooms when I feel like it.