The data sync between the BB, the SW8, and the command station can get a little wacky if they use different power sources. Try a couple different sequences of powering different things on first. The SW8 and the BB can be left on 24/7/265 with no issues. That is how I have them setup with external power on my layout. The three data lines between the BB and the sw8 are extremely sensitive to outside interference since it is a 5v low voltage connection. Twisted wires, very short wires, even some type of shielding might improve the situation. I use Cat5e /CAT6 cables with 24 AWG twisted pairs for all the low voltage (5v) data lines on my layout.
NCE recommends that buttons or toggle switches be connected to the Button Board with
wires less than 2 feet in length. Longer wires may be used if you twist them together
(about 6 or more twists per foot) or use pre twisted wire
Make sure you have your Button Board connected to correct terminal on the SW8. If your SW8 has two terminals for external connections make sure you only use the one specifically labelled for the Button Board. Do NOT use the one labelled for RELAY BOARD.