I just noticed this odd search behavior when entering a new blu-ray movie, Top Gun, on my iPad. I searched in US by title and it returned nothing. Odd? I searched in ANY and it worked fine, returning US blu-ray titles. I deselected Blu-ray in my US search and it returned DVD titles. At first I thought was an iOS 17 issue, so I used my old iPhone running iOS 12 and the same thing happened. I did the same search on my PC and it worked fine. I also entered the UPC code in a US search on my iPad and it worked fine.
I guess the point here for iOS users is to try different things if your title search returns nothing. Searching by UPC seems to be the most reliable.