There’s something off with the system.
It’s broken on Firefox Developer Edition. Clicking on the “Follow” button on the artist’s page yields nothing but this error on the console:
The artist also doesn’t show up on my following list and his followers count doesn’t change.
On Chrome v52 the button changes to “Following” and his followers count change, but the artist still doesn’t show up on my list, making it look as broken. The artist will appear after ~6 hours though.
Unfollowing people already on the list also isn’t working properly. On Firefox, directly on the artist’s profile, 90% of the time the button works, it changes to “Follow” and the number changes. The unfollowed artist remains on my list.
Other times something goes funny with the servers and unfollowing someone counts as +1, following count as as -1. (yes, it allows to “follow” someone in FF if it’s undoing an unfollow) Pretty sure this one is a cosmetic issue only.
No errors on console during the situations above.
Then there are the times the button is completely unresponsive. In this case, it throws up exactly the same error I’ve attached before. I didn’t manage to replicate this error properly, some profiles you can unfollow without problems, others you simply can’t.
Chrome unfollow always work, but looks as it doesn’t due the long delay in removing someone from your list.