I may be having a similar experience. I am an Admin on our forum. I changed my email address, received the verification email - okay so far. Upon going back to my forum - I get logged in automatically - I checked my settings. Forum emails are set to my new address, however… login email is the same as originally registered. I did some checking and found out I have to login in to my Admin account with the same address used when first registered. If I completely log out and try to log back in with my “new” email address, I get the same error message as you.
Check you preferences to see if your email address to receive forum emails is set to your new address. It probably is. But I bet the address for logging in is still set to the one you used when you first set up your Admin account.
Maybe @Dax or another team member can explain if this how it is supposed to be or if the Admin login email has to be reset another way.