I posted twice last week on this topic and found many similar threads across the net,so thought I would post back on what solved my problems.
In the end the fault came down to the firmware on the drive. I have a HL-DT-ST BD-RE GGW-H20L drive and the firmware was YL03, now at YL05.
This drive has written to bu ray media before. The description in the firmware shows a number of extra media strategies included for writing, so even if it has written blu ray before it needs this to work with newer media.
One of the things I have changed is to remove cdrkit and replace with cdrecord package, many posts discuss this and if you want it you need to add the repository at Index of /repositories/Base:/System/openSUSE_Factory remove cdrkit and find cdrecord also picking up dependencies.
I had changed to cdrecord and also tried on ubuntu and nero before finding fix. I would think I could now return to cdrkit, but it now works and if it aint broke...
My burner is now working happily with k3b and has written 11G mkv files to blu ray wthout any further problems.
I hope this is of use to others with problems.