Symptom:
When querying directly via the API in some cases it can take an excessively long time (10+ minutes) to return results, and in extreme cases no results may be returned.

While using the "Search Recording by Participants or Tags" search box in the Search & Play interface after a 3 minute timeout, no results are displayed, and the error "The server failed to fulfill an apparently valid search request." is returned.

Conditions:
This can occur with MediaSense 10.0(1) and later S&P when numerous values are entered in the search field seperated by spaces to search for multiple participants or tags.

A query via API using "AND" terms between clauses matching different TAG values can trigger this issue. 

20+ values in the query is often problematic. The problem is sensitive to the number of RecordingSession records - if you have less than 1,000 records the problem is not likely to occur even with 20+ values; if you have 3M+ the problem can occur with as few as 8+ values.