It seems you have issue with search indexing, unless any content is indexed it is not searchable.
The index is not run immediately.
It seems the search works fine regardless of case of search keyword.
Try a search for one word in all lower case, and the same search for one word in all upper case and if you can still stand by your statement, I will believe you.
Hopefully you can direct their attention to this it has cause a number of us to miss tasks that exist, but do not show up on searches because case wasn't matched.
This is a high priority but very very simple fix.