He's in Paris so I assume that's for visa reasons, seem to remember Mo went there on his way to us.
It is, according to The Times:
Meanwhile, Liverpool’s new signing Luis Diaz is in Paris as he waits for a visa to be processed that will allow him entry into the UK. The Colombia winger would then have to attend a work-permit hearing.
Should the 25-year-old, signed from Porto for £37.5 million rising to £50 million, be able to train with Jürgen Klopp’s side on Friday, then
he is likely to make his debut in Sunday’s FA Cup tie with Championship side Cardiff City