I use Trello for business purposes with an Gmail-account run by my office. After receiving an invitation to a private board on Trello I tried to register with my personal Gmail-account. After submitting my e-mail-adresse via Apple Desktop app, I was redirected to the website and to an 405 error. Since then I can't use Trello anymore – not business-wise, not personal-wise.
What to do? Any hints are welcome.