Canno't fix Director name because a restriction with uppercase letters

I recently made a contribution. The film is "Nyctibius": https://www.imdb.com/title/tt15426178/?ref_=fn_al_tt_1

The Director is "DN Bianco", however, I had to use "D.N. Bianco", because IMDb warns "Bianco, DN ends with an uppercase letter and is therefore invalid".

I you do a simple search on IMDb.com, you will find people as:

PJ Harvey

or

FKA Twigs

Both of them have and ending uppercase letters in their first names, so, it seems they have no problem to add their names correctly.

I tried to fix my name, but it can't be done through the regular proccess because it keeps giving the same warning: "Bianco, DN ends with an uppercase letter and is therefore invalid".

How can I get my name fixed?