Mac Pro 2023 will not boot with PCIe SSD installed.

I just spent all night setting my new M2 Mac Pro. Everything seemed OK. This morning I was ready to do the final steps and get back to work. The final steps included adding some additional storage for my audio projects. Something I've been doing for over two decades now and didn't expect that to be a showstopper.

As soon as I installed my previously working OWC SSD OWC Accelsior 4M2 the Mac Pro would NOT boot. This drive works and I put it back in my 2019 Mac Pro and there are no issues. Even if I put the OWC SSD in a Sonnet PCIe to Thunderbolt chassis, the same thing happens. No boot. If I connect the chassis when the Mac is booted, it freezes.

I had also purchased a new OWC Accelsior 8M2 and planned for it to be my main working audio drive but the issue also happens with that SSD, so it's safe to say it's not a faulty SSD.

OWC is a VERY reliable brand and widely used in the pro audio and video community. I've been using them over 20 years now without issue.

I am not using these drives to boot the MacOS from. These are just storage for my actual audio projects, which is common in audio studios to have a dedicated drive for all the audio work. No software runs from these drives. I am using the internal Mac SSD to boot from as you normally would and without the PCIe SSDs, the computer seems to run just fine. I was so excited to get to work but I can't use this machine and get by on just the internal storage. Additional PCIe storage is essential in a pro studio.

I chatted with Apple Support today and they are looking into it, but I don't feel too confident about it. The "senior advisor" was not even aware there was a new 2023 Mac Pro (LOL) and hadn't watched the WWDC yet. I thought he was joking. He was not.

I called OWC as well and they are not aware of any issues yet but the Mac Pro just started arriving yesterday so it's still new territory. I'm trying to find out if it's an OWC issue, or Apple.

I do have an OWC Thunderbay 8 with 8 HDD (my project archives) and that did work OK.

Something about the new Mac Pro is NOT happy with PCIe SSDs connected either internally, or in a Thunderbolt chassis.

After staying up all night and wasting about 10 hours of setting up the new 2023 Mac Pro, I am sadly back to working on my 2019 Mac Pro. All my OWC SSDs work just fine again when inserted in the 2019 Mac Pro.

This could be bad news for Apple if it's on their end.