Error with displaying some artworks – pixiv Review

A lot of the artworks don't show up in the app, I'm not talking about those R-18 stuffs. I meant almost half of some artist's works, and they aren't even remotely r-18, they just never show up in the app for no reason. Unless I chose to bookmark them on webpage, then they'll show up in the bookmark list in the app.
Review by The user name is always taken on pixiv.