500 Internal server error when setting custom notification email for group

Hi everyone!

I had two GitLab accounts, one with a company email address, one with my own. From the start I used my own account for accessing the company group, but I wanted to receive notifications from that group in my company inbox, so I went ahead and deleted the account with the company email, added that email to the other account and verified. So far so good, but when I try setting the company email address as a custom notification email for a group I get internal server error.