I've noticed for some time a bit of, well, weirdness in the Role column on the Credits and Musicians tabs (for tracks and albums): autocompletion only works if you click (once) on the down arrow that opens the list of pre-generated choices.

Each section, ie. Authors and Performance, Production, Band Members, Guest Musicians exhibits this behavior.

It would be a step saver if autocompletion worked without having to open the list of possible choices.