Percolator not matching queries it should, reindex the query fixes the problem

Hello,

My team recently launched an application that uses Percolate. We are running ES 6.4 in AWS and are seeing a very strange issue where percolate is not matching queries that it should match.

Those queries exist in the index, and they are searchable. We are not able to reproduce the scenario but we can consistently fix the problem when it occurs by reindexing the query. The source for the query that matches and the query that does not match are identical. Reindexing the entire percolate index also resolves the issue for a few hours.

There are about 7,000 queries in this percolator index. I have read that past versions of elastic search required the entire percolator index to reside in memory. I am wondering if that is still the case and if this is a common problem others have ran into with percolate.

Thanks for your help