thanks to everyone who responded. spoke to jamf support and looks like I'm hitting a bug.

Adding this as an after script to configs with recovery partition seems to be working.

bless -mount /Volumes/Macintosh HD -setBoot

@CasperSally I'm catching up with emails around JNUC time.

I'm curious how the OS.dmg is being created.

@bentoms - it was from composer.

Hi @CasperSally

I've had this bug for the past two years.

JAMF insisted this is an Apple issue but it sounds like you got better support where you are, this was how they closed my ticket :/

*Thanks for your feedback. From what I am seeing in the case we are facing Imaging Fusion Drive iMacs? For the one that works are they also Fusion drive? If they are all fusion drive, I see that my colleague sent you already the information on how to image iMacs with Fusion drives: https://jamfnation.jamfsoftware.com/discussion.html?id=9869 Did you try changing your configuration to SSD drives or keep the standard slow spinning drive to see what happen? We know that deploying to Fusion drives is al little bit complex and the issue is not from our side, but there is no other KB about imaging a Fusion drive besides that thread. Please let me know if any further questions.

My instruction to the techs has been to boot to recovery partition and set the startup disk, then reboot, clear NVRAM. The Mac should then boot up normally.

I'll give your method a go, thanks for sharing.

@andysemak my issue wasn't with fusion drives nor fixed by setting startup disk, but i hope the bless command helps you.

FYI anyone seeing bless command issue - it's labeled as defect number is D-009763 - please report it if you see it too.

I don't see this defect listed under fixed or known issues in the 9.82 release notes. Not sure if it was fixed but guessing not.

The bless command no longer works with 10.11 netboots (SIP). Others must have ran into this? Right now we're unable to image new hardware that requires 10.11 netboot if there's a recovery partition in place.