Mass Editor not working. Keeps trying to load in, or log in. Seems to be stuck in a loop.

Trying to use the mass editor, but it seems to have broken. It will either ask me to login, or it will just keep trying to load as though it's already got the credentials, but wants to validate again. The other activity is it will just cause a list view to load indefinitely until I refresh the page, then it will reset, but still won't work.