Hello @bfa,
Welcome to the Toradex Community 
Could you please try and see if this solution works for you?
As @jeremias.tx suggested, I tried with the command mount -o nofail,uid=1000,gid=1000,umask=007 $dev /var/rootdirs/media 2>/dev/null || true and it seems to work for me.
Please let us know how it goes.