I’ve added editors (all showing as pending) and just now after one of them pointed it out to me that they were unable to create their users. So I tried to send an invitation to myself (to a secondary email) and had the same problem: the link leads to a page but never presents the editor creation form at the bottom of the page as usual.
My guess is that it has to do with redirect and the setup I have for multilanguage (no and se). When you access the domain https://campcloud.24sevenoffice.com/ it redirect you to https://campcloud.24sevenoffice.com/no (norwegian.
I can create a link for new editor and add here if you think you can help me! 
Hope somebody can help me with this!