Changing username doesn't allow capital letters or spaces?

[carbunclecards]

So I want to change my username and it doesn't allow me to use capital letters or spacing between words. Is this new or something can I not do that anymore? I see some sellers have theirs with capital letters and spaces but I wasn't allowed to do it which is disappointing. Any help or advice to get around it would be appreciated 

[**peaseblossom**]

I think shop names can be in caps but as far as I know the actual account IDs have always had to be in lower case with no spaces.