Subscribe/unsubscribe actions not functioning

[Clorith]

Subscribing to a thread when you post a reply works as intended (the checkbox under the post box), but if you wish to edit subscriptions they do not work.

This means you can not subscribe using the link in the sidebar, nor can you unsubscribe from the sidebar

You also can't unsubscribe using the Subscriptions list on your profile.

[netweb]

Duplicate of #1980.