Use this Oracle Database Script to find Stale Materialized Views in Oracle.
What are Stale Materialized Views ?
Stale means that using the materialized view would yield a different result than using the base table.
You can fix this by:
Manually refreshing the view. This is useful when data is written periodically (loaded once an hour).
Configuring it for fast refresh on commit. This is useful when data is updated more frequently, and it means that whenever one session commits, the materialized view is updated.
Accept stale data (changing the parameter query_rewrite_integrity to STALE_TOLERATED). This is useful when dealing with higher level aggregates.
Any here is the script to identify Stale Materialized Views in Oracle.