"Other duties as assigned" has scope and intent. In other words, they can assign you cafeteria duty, or after school bus line duty whatever. What is OUTSIDE the intent is changing what classes you are teaching, etc.
If you call your organization, you could fight this and win. Unfortunately, there's a good chance you'll be job hunting next year too. It's disturbingly easy to put teachers on a growth plan and non-renew them if you really want them gone for not being a team player.
Sucks, but it's your call.