where is my purchase history on itunes after Catalina?

I wasn't intending to suggest a fix, just to indicate one of the ways purchase history can be accessed. I'm not sure what is happening but I have not seen any other reports of installing Catalina affecting iTunes purchase history.

When you click on "See All" in the directions in the previous reply, what happens?

The following may also have something that will help: https://support.apple.com/en-us/HT204088

Open the Music app, click Account in the menu bar at the very top of the screen, then click View My Account, then in the Purchase History section click See All.