I have no problems to create working backup (checked with OpenATV 6.2 and 6.3) even when I have similar error message.
Anyway - when flashed same or different H9 Twin with my backup image - after flashing - these boxes do not see wifi card and only LAN is working ;-)
Trying with OpenPLi 7.1 and backup suite - but is not working at all (backup creator)
I have trying to create backup on sandisk pendrive (16GB) also with SSHD 500GB - same results
