after resetting my phone i had to do this all again, and i noticed the same thing. you need to download a different version of the album (as in download it from a different website) and change the titles of the songs before proceeding with adding them to your local files. I think this is because spotify tries to link it with their database of the song's info for genre, artwork, etc. but it glitches since it isnt available on spotify.
[what i did that seems to work is adding the track number before the name]
It's not about what Spotify does though it's how chance released the music. He didn't put it on any streaming services or iTunes because he wanted to release it as a free download. Look at my other answer which is an accepted solution on this thread to see how to get acid rap on your personal Spotify library.
Yeah i know that but maybe spotify could talk to him or somthing, all i know is that i would love it if all his albums were on spotify. And somehow they got the Coloring Book on spotify (or chance did) but that means that it could be possable to get his other albums (but im no expert in this stuff sooooo, yeah)
I think they have patched it. I have switched to Apple Music (shh) and it allows to integrate downloaded songs into your library extremely easily. Not trying to advertise just trying to help. You can always try restarting all your apps in your recently used tray, and turn off your phone. Go to your settings on your pc and turn off your "local files" path where your songs are and add it again. Try everything again and once it's done, turn on your phone and check your playlists with an internet connection.