Is that an embedded device with a small address space? APE used to require a 47bit address space. The release I published today fixes that. Maybe give it another try?

No, it's a server with 256GB of RAM, but indeed the kernel config has CONFIG_ARM64_VA_BITS_48=y (and 52 for userspace). I have since moved away from this kernel, I'll see if I find the time to boot it again to test the latest memory map manager.

Edit: I tried booting it, the issue is still present, I updated the github issue.