Why is my refresh using a complete instead of a fast?

I'm using version 11gR2

I logged on to DB1 on Server1 as user1 and created a materialized view log on table1

I then logged on to DB2 on server2 as user2 and created a materialized view table1_mv on table1 using REFRESH FORCE ON DEMAND. The query is a straight select * from table1@dblink_to_db1

Noone is currently using the table so there have been no inserts/updates/deletes.

I then ran:

begin

   dbms_mview.refresh('user2.table1_mv');

end;

/

As I understand it, a FORCE refresh should be run. It would attempt "a FAST refresh is one is possible or a Complete refresh if a fast is not"