If this is a software issue and not an issue with the actual disk, I believe you can achieve iso9660 format using xfburn:
sudo apt-get update
sudo apt-get install xfburn
xfburn --transcoder=basic
ref: works with format iso9660
&
:~$ xfburn --transcoder=list
Valid transcoders are:
basic Can only burn uncompressed CD quality .wav files.
gst Uses gstreamer, and can burn all formats supported by it.
However, it may not be possible to not have a UFS burned disk as one of the advantages of UFS implementation over iso9660 is the ability to work with CD-RW disks as iso9660 is readonly and CD-RW is of course re-writable.
http://www.axis.com/files/tech_notes/cd_formats.pdf
https://en.wikipedia.org/wiki/ISO_9660
https://en.wikipedia.org/wiki/Universal_Disk_Format