That’s actually the expected behaviour unless I’m mising something here.
If you change the mobile breakpoint to 2000px, that means the mobile menu will kick in at 2000px which means you will see the mobile menu at basically any device so off-canvas panel option becomes irrelevant.
So you want the off-canvas menu on mobile only? If so what happens if you set the breakpoint back to 768px with the option mobile-only?
Let me know if I’m still missing something π