I have taken latest code from upstream and found the commit

is causing Virtual media feature to fail. This commit is created to fix issue #3814 .
I analyzed the bug and found that the function which_dev in file meta-phosphor/recipes-connectivity/jsnbd/jsnbd/state_hook always return first UDC and when I try to access this port it says "Device or resource busy" when I revert this commit and use the code where device name hardcoded virtual media feature works fine.

Could you check why function which_dev returns a busy UDC