Cannot save radio after deleting content of artist and importing it again
I've removed all content from one artist (let's call them 'artist A') by accident (instead of duplicated song). Then, after I realized what I did, I've imported songs from this artist again.
Some time later, when I tried to update my radio with a new artist, I couldn't save the radio. I had to remove 'artist A' from the filter and add it again. Then I could save the radio just fine.