Hi sugarplumsss,
In principle, you do not necessarily need the Style Category buttons. When playing live, you usually work with Registrations anyway and don't call up Styles directly, at least not Preset Styles "as is" (without any adjustment).
Alternatively, if a Style Category button is broken, like the R&B button in your case, you can press any other Style Category button to open the Style Selection display. Then press the upper display button [8] ("UP") . This will bring you up one folder level, i.e. "out of the current folder". Now you see ALL Preset Style Category folders and can select the desired folder.
When you are in the MAIN display, press the display button [D] to open the Style Selection display. If you are already in the Preset drive, press "UP" (as described before) and select the desired other Category folder. (Of course, if you're in a different drive (User, HD1, or USB1) after pressing [D], you'll need to go to the Preset tab first.)
It happens again and again that certain panel buttons stop working. Very often this affects the display buttons (A - J) on Tyros models. The only permanent remedy is to have the relevant button (or ALL similar buttons in the relevant panel section) replaced by a technician. Sometimes it helps temporarily to press the button in question very often. Some users had already reported that faulty buttons worked better again if you "sucked off" the button with a fine vacuum cleaner nozzle for a long time. In my experience, only replacing these so-called "tact switches" helps in the long term.
If you copy Preset Styles to other drives, you don't need to rename them. But it doesn't hurt to change the Style name (e.g. add a number or a letter at the end) as soon as you have changed a Preset Style in the Style Creator and saved it again. (Simply to avoid confusion with the original Preset Style.) If a "non-Preset Style", i.e. a Style that is stored on one of the drives USER, HD1 or USB1, is already used in Registrations, the Style may of course NOT be renamed (or moved) afterwards. Otherwise you would have to re-memorize the Registrations in question with the renamed/moved Style.
Hope this helps!
Best regards,
Chris