Search not working in Photos High Sierra

I have 5000 photos on my MacBook 12 Retina, these are shared on my iPhone and iPad.

I have just tried to bring up a photo of my dog, of which I have hundreds of photos. So I opened photo on my Mac, typed "dog" into the search and returned no results. Which is strange as it worked fine last week.

I also tried searching for "Car", "Boat", "Cake", "House" and lots of other things I have photos of, but they all returned no results. I did all the above searches on my iPad and iPhone and they worked perfectly. Searching "dog" on my iPhone returned 371 results, yet I get zero results on my Mac with the same library?

Does anybody know why I can no longer search for a photo on my MacBook?