Bullet points list for easier reading/understanding:

* I have several 23H2 Instant Clone Pools running fine (image from late '23).
* Figured that I need to update to 25H2 as 23H2 is no longer supported.
* Couldn't in-place update because of 'Winternal' problems I have been unable to fix.
* Decided to rebuild everything in a new W11 GM from scratch with 25H2 ISO.
* Installed OS, Tools, Agent, Updates, Software, Omnissa OSOT & debloated.
* GM runs perfectly.
* Created a new Instant Clone Pool with this new GM → VMs **won't boot**.
* Pool creation stuck in Customizing, VMs can't find boot device.

In the past I have been using *VMware Paravirtual* SCSI controller as disk controller. With the new GM VM I chose a *NVMe controller* instead because of some VMware employee's suggestion that this is now the way forward (lower latency, more speed and throughput etc.). In my memory (besides newer OS and software) this was the only thing I did differently than before.

There's [a KB article out](https://knowledge.broadcom.com/external/article/327088/sometimes-instant-clone-vdi-gets-stuck-i.html) adressing this issue but the proposed workaround does not work for me. I already put much work into customizing this new image and I would like to prevent having to rebuild everything again just because the controller isn't suitable for use in an Instant Clone environment.

Does anyone have an idea if this controller *really* causes the issue – or if it doesn't, what is? As mentioned I can boot, shutdown, re-boot the GM VM fine without any issue, doesn't look like a timeout to me, something else seems broken. Any help is greatly appreciated!

New W11 Instant Clone Pool stuck in Customizing – VMs showing EFI menu, can't find any boot media