This has happened twice in the past two days. I deleted and reinstalled the app the first time but wanted to report before doing that again. I have an iPhone 16 Pro, iOS 18.5
FYI: After 4-5 hours, I was able to use the app again. Seemed like it was just a long lag. When I add a title from the title's main page, it seems to not lag (so maybe it was because I was adding from search results)