OK so this is weird, failures starting to happen again. I use a custom custom catalog that has a custom name for my Output Volume Name:
# 10.8.x + ORG CUSTOMISATIONS
#################################################
ISO Language Code: en
Output Volume Name: System
Output File Name: MGi-10.8.4_GM_YYYY_MM_DD.dmg
include-file: 10.8_vanilla.catalog
#################################################
The debug log shows that the its erroring unable to find volume Macintosh HD...
I've tried clearing Cache and /tmp then rebooting but no good. I ran 10.8_vanilla and it worked without any problems,
Current image mount point: /private/tmp/idmg.leDd/idmg_mp.wekZ
Shadow file location: /private/tmp/idmg.leDd/C4126577-2C5C-4810-9298-8F88638CA998.shadowfile
Mounting the shadow file (/private/tmp/idmg.leDd/C4126577-2C5C-4810-9298-8F88638CA998.shadowfile) onto the cached image (./Caches/BaseImageCache/AF6E80F2.dmg)
Recovery Partition Found
/dev/disk2 GUID_partition_scheme
/dev/disk2s1 EFI
/dev/disk2s2 Apple_HFS /private/tmp/idmg.leDd/idmg_mp.wekZ/System
/dev/disk2s3 Apple_Boot /private/tmp/idmg.leDd/idmg_mp.wekZ/Recovery HD
Target OS: ()
WARNING: Chroot jails only work with 10.5, so disabling that functionality
WARNING: Installer daemon-jailing does not currently work with 10.7, disabling that functionality as well
10:21:53 ###### Beginning Update Installs from /private/tmp/idmg_temp.R8Y4Ay/items-h8rXWL ######
Working on folder 01 iTunes 11.0.4 (10:21:53)
Mounting the package dmg: iTunes11.0.4 sha1-cd9f00b54f2c7b2b46083f8c3d2813e0b3bc3b30.dmg (/private/tmp/idmg_temp.R8Y4Ay/items-h8rXWL/01 iTunes 11.0.4) at: /private/tmp/idmg.leDd/idmg_mp.q9GL
Mounted disk image from /Volumes/Data/Users/cgerke/instadmg/Caches/InstaUp2DateCache/iTunes11.0.4 sha1-cd9f00b54f2c7b2b46083f8c3d2813e0b3bc3b30.dmg at /private/tmp/idmg.leDd/idmg_mp.q9GL
Installing Install iTunes.pkg
Error trying to locate volume at /private/tmp/idmg.leDd/idmg_mp.wekZ/Macintosh HD
"disk3" unmounted.
"disk3" ejected.
Unmounted the Package DMG image from /private/tmp/idmg.leDd/idmg_mp.q9GL
Folder 01 iTunes 11.0.4 done (10:21:57)
So my workaround for now is to clear tmp and cache every time, then run 10.8_vanilla only, then run my custom catalog. Anyone else getting this?