Search seems to persistently fail for certain namespace selections, but not others, even others that include those selections.
Example: searching on en.wikipedia for 'huggle'
(article) - works
user only - works
user talk only - fails
project only - fails
project talk only - fails
user + any of [user talk, project, project talk] - succeeds and returns pages from all the selected namespaces
By 'fails', I mean displays the "Note: unsuccessful searches are often caused ..." message, even though results clearly exist.
This has occurred every time I've tried in the last two weeks; reloading, clearing cache, using a different browser, machine or IP address does not fix the problem.
The problem is compounded by the fact that I am unable to use an external search engine to obtain many of these results.