growisofs hangs closing disc

Example, I was burning an Ubuntu .iso file, as follows:

# growisofs -dvd-compat -Z /dev/rcd0c=ubuntu-16.04.3-desktop-amd64.iso
Executing 'builtin_dd if=ubuntu-16.04.3-desktop-amd64.iso of=/dev/rcd0c obs=32k seek=0'
/dev/rcd0c: "Current Write Speed" is 16.4x1352KBps.
34340864/1587609600 ( 2.2%) @6.9x, remaining 4:31 RBU 100.0% UBU 11.1%
66617344/1587609600 ( 4.2%) @7.0x, remaining 3:25 RBU 100.0% UBU 97.2%
84869120/1587609600 ( 5.3%) @3.9x, remaining 3:32 RBU 100.0% UBU 98.6%
107610112/1587609600 ( 6.8%) @4.9x, remaining 3:40 RBU 100.0% UBU 98.6%

[...]

1501757440/1587609600 (94.6%) @10.7x, remaining 0:07 RBU 100.0% UBU 97.2%
1541439488/1587609600 (97.1%) @8.6x, remaining 0:03 RBU 100.0% UBU 97.9%
builtin_dd: 775200*2KB out @ average 8.4x1352KBps
/dev/rcd0c: flushing cache
/dev/rcd0c: updating RMA
/dev/rcd0c: closing disc


It just hangs there and I have to kill ( pkill -9 growisofs ).

The burned disc does work.

Any ideas? Is this somethimg more likely specific to my hardware?

From dmesg:

cd0 at scsibus1 targ 3 lun 0: <HL-DT-ST, DVDRAM GH24NSC0, LI00> ATAPI 5/cdrom removable

Allan