fatfs and usb_cdc_acm

[andy]

"diskio_blockdev_register(drives, ARRAY_SIZE(drives))"

this code affects the usb_cdc_acm work when this code after the app_usb_start.

[Kenneth]

I can see you already have an on-going case here with the same question:
https://devzone.nordicsemi.com/f/nordic-q-a/74156/the-fatfs-example-is-work-but-dont-work-in-my-project