I noticed this problem about a year ago, but did not dare to write. Most of the songs I bought are not available to me. In the "purchases" they are absent. And if you find them in the search, displays, then they are in my purchases.
iPhone SE, iOS 12
If you mean that they aren't showing in the Purchased section for redownloading, and if they still in the store and if you haven't moved countries since buying them, check to see if you've hidden them : Hide and unhide music, movies, TV shows, audiobooks, and books - Apple Support
If you mean that they aren't showing in the Purchased section for redownloading, and if they still in the store and if you haven't moved countries since buying them, check to see if you've hidden them : Hide and unhide music, movies, TV shows, audiobooks, and books - Apple Support
problem with iTunes
