I have same problem on my Omega2S+ with emmc (Image: omega2p-v0.2.1 b199)
my logread:

Thu Feb 21 01:23:53 2019 user.crit mountd[1328]: could not find a serial number for the device mmcblk0
Thu Feb 21 01:23:53 2019 user.crit mountd[1328]: could not find a serial number for the device mmcblk0
Thu Feb 21 01:23:54 2019 user.crit mountd[1328]: could not find a serial number for the device mmcblk0
Thu Feb 21 01:23:54 2019 user.crit mountd[1328]: could not find a serial number for the device mmcblk0
Thu Feb 21 01:23:54 2019 user.crit mountd[1328]: could not find a serial number for the device mmcblk0