maple not working unless usb plugged in

[guest]

ive had trouble from time to time
using the maple when the usb isnt plugged in
or its plugged in to a computer that isnt talking to it directly

this workaround made it work for me

include "nvic.h" at the start of the sketch
call "nvic_irq_disable(NVIC_USB_LP_CAN_RX0)" from within setup()