Hello! I am working on fixing the issue.
Yes, for some reason the “noapic” argument is causing the problem. I do not understand why at all that is being added as boot option.
I provide a comment in 2295026 – 6.8 kernel see all cpus, 6.9 only sees 1 cpu explaining a possible workaround, it would be worth trying it out.
I am now investigating where is the “noapic” coming from.