I have tried two days in a row to transfer a character from my main account to a secondary account (yes, both meet the same name requirement) only to have it be denied with the error:
-The destination realm already has the maximum number of characters allowed.
Both accounts are:
Have active subscriptions
Have less than 50 characters total
(the account being transferred to only has 23 total)
In my second attempt on the second day, I actually attempted to transfer it to a realm where I have ZERO characters and it still failed.
I will be putting in a ticket but also posting this here in case anyone else is also experiencing this or already has found a solution.