"Enter a valid EA ID." Error Message is Useless

All I'm trying to do is change my EA ID from "CT-Sapper" to "[KDM] Sapper".

I would be more understanding if this error message was actually explaining the issue to me but come on EA seriously? Why is it so difficult to slightly change my EA ID? I know for a fact that it's been more than 30 days since the last time I've changed my EA ID and I've tried every variation I can think of; adding dashes, spaces, underscores, lowercase, uppercase, adding numbers, removing the brackets, using alternate characters for letters etc. and absolutely nothing works.  And when I contact EA Support for help (and finally get through to an actual person) even THEY aren't able change my EA ID??? All of the other threads on this issue are also absolutely useless. EAs recommendation so far? "IDK man try something else until it works". Who is running this company's service department? Is it Keyser Soze??? Is it a herd of sheep all somehow wearing suits in a field on the side of a Swiss mountain??? Nobody knows! Not even EA knows!

Please for the love of my sanity, just let me change my EA ID without having to go through a 25 step process and providing useless error messages like "Enter a valid EA ID."