بسم الله الرحمن الرحيم
(Fatwa: 630/537/H=04/1435)
The Ibadi sect which exists in Oman Sultanate is a branch of Khawarij sect which is out of the fold of Islam. Salah behind the imam of this belief is invalid. (Ahsanul Fatawa 1:198) So, you should perform salah individually.
Allah knows Best!
Darul Ifta,
Darul Uloom Deoband
