Some local files won't show up when dragged to songs tab

[Buschy_1]

I'm pretty new to Spotify and am just trying it out for now. Some albums I own aren't on Spotify. I've been dragging songs into the songs tab under "your music" but some won't show up and some will. I just want to be able to shuffle all my local files along with Spotify songs I've saved. Some albums I've dragged will show up as albums but some won't. The songs are in mp3 format by the way. I haven't been able to find any solutions for this yet. Any help would be appreciated!