I did some searching and found several transactions on nem that matched your address and roughly matched your date and estimated xem amount. But I eliminated most of them since they had some message in the transaction or for some other reasons. Here is a likely candidate for your nem transaction:
http://explorer.ournem.com/#/s_tx?hash=ebe35c69a33b6de090b9267c088690fa76c782129731e07c2d4eca902d128469
I could be wrong of course and the only way to be sure would be to ask shapeshift.
Does the transaction for 784.9091 xem ring a bell?
Transaction Detail
Hash ebe35c69a33b6de090b9267c088690fa76c782129731e07c2d4eca902d128469
Timestamp 2018-01-08 21:29:50
Type transfer
Sender ND2JRPQIWXHKAA26INVGA7SREEUMX5QAI6VU7HNR
Recipient NA2KC36U4YIHDVMBEKGGFWBGOIVJMB5XAM7X2ETI
Amount 784.9091
Fee 2
Block 1450865
Message