I've never been able to search the forum using the "Show results as Posts" option (as opposed to "Show results as Threads". It returns a page with:
An error was encountered
Error: Unable to fetch search results.

This renders search virtually useless for me. who would want to sift through a topic of possibly 10/20 pages to find 1 post.

Where do you see this option?

click search , and look down to Select how to view search results

Yeah it seems to bug a bit.