cannot create a fast refresh materialized view from a complex query

[slimdave]

Your MV will have to be based entirely on data in the table(s) without reference to sysdate.

A simple approach would be to include a column that states whether the row is to be included in the MV or not, filte the MV by that column value, and update it peridically (every month, I guess) to generate the incluion of new rows into the MV.