We have this now on 4 pc's in the office.
Nothing works we can not get any results, even in a folder where there is one document he can not find the document in the search bar.
I hope Microsoft fixes this fast.
I even reinstalled windows on one pc but still nothing helps.
Disabling web search on the search bar resolved the issue for me after none of the other solutions worked.
Here is a link on how to do that.
Alternatively, you might want to find a link that has pictures as this was difficult to follow.
If you are using windows pro or enterprise there is a way to disable we search in the group policy settings, but I cannot comment on whether or not that that resolves this issue.