Problem switching from rekordob to usb

I upgrade my cdj2000 nxs2 to 1.40 when i play with rekordbox dj connected in hid mode, if i want to switch the cd that is not playing to usb , also the audio that the cd is playing stops for 5 seconds. With the old firmware i cam switch wothout problem from relordbox to usb. What i have to do can i downgrade??