Search filters like prefix: and intitle: are not working from the search box.
Topic on Talk:Search/status
Which wiki? Can you provide an example?
This is en.wiki with the new search engine checked under my preferences in beta. Here are some results using the filter "prefix:Mechanical"
As you can see, the Cirrus results do not have the search term in the title of many results at all, let alone as a prefix.
Seems to be following redirects (ie. "Mechanical and Aeronautical Engineering" > "Engineering").
Well that's still a problem. First of all, it is not transparent that redirects are being followed, I am being presented with the top result of "Engineering" which patently does not match my search specification and no indication of why it was included. Secondly, while I might possibly (or possibly not) have wanted to know about redirects, I probably don't want them at the top of the list. If redirects are going to be included, the name of the redirect should be in the results, not its target, it should be marked as a redirect, and it would be rather useful if it could be optionally suppressed.
The whole reason a user would use the prefix filter is they want exactly those pages that match. Not pages that are associated in some way.
Filed at bugzilla:65232 and I'll look at it now.
And I've submitted a patch to fix it (https://gerrit.wikimedia.org/r/#/c/132973/). If all goes well we'll merge the patch in a few hours and this'll be fixed on enwiki a week from Thursday. We can get it faster if it is really killing you.
It's not urgent as far as I'm concerned. While it's still a beta function it can be turned off. You might want to look at bug 65237 which I just raised before you patch anything though.