I have had an RFE for my Eb5 I -829 petition and my attorney submitted my RFE 3+ months ago but haven't heard anything back. Is it true that USCIS responds to RFE within 3 months or have you seen delays in RFE processing in Eb5 cases?

We've definitely seen a slowing down of USCIS adjudications particularly when an RFE is involved so this delay isn't unheard-of.