Deficiency Memo received for refund

We filed an application for refund of ITC on export without payment of tax. We attached the following as supporting documents: LUT, GSTR2A for the period, BRC code and list of invoices. We uploaded the statement of invoices too.

However, we received a deficiency memo twice with the notice saying :"Supporting documents attached are incomplete" and "Document: main document".

It makes no mention of what other supporting document they require. Kindly help!