Missing indexes statistics is missing on SQL Server 2008 R2

Missing indexes statistics is missing on SQL Server 2008 R2

I have an installation of SQL Server 2008 R2 (one of a few) and it's
reasonably busy system. I'm trying to optimise some of the indexes like
I've done in the past by using information from missing indexes tables.
What seems to be strange is that sys.dm_db_missing_index_group_stats table
is empty?!
Now I don't believe for a second that none of the databases on that server
misses a beat and other tables like sys.dm_db_missing_index_group_stats,
sys.dm_db_missing_index_group_stats, etc contain plenty of records.
Just now I've seen 1 (one) record briefly appearing in that table and it's
gone since then.
I wonder if something is seriously wrong with that server or if I'm
missing a trivial