Ubuntu 20.04.2 autoinstall cloud-config fails

I'm PXE booting and auto installing a 20.04 server without success. The server is acquiring the user-data file from my cloud-init server however it fails at the some point on each install, convert_autoinstall_config: max() arg is an empty sequence

For reference my ipxe params:

kernel vmlinuz root=/dev/ram0 ip=dhcp hostname=test url=http://releases.ubuntu.com/20.04.2/ubuntu-20.04.2-live-server-amd64.iso autoinstall ds=nocloud-net;s=http://server/configs/
initrd initrd

and more excitingly, my user-data (simple example from Canonical to test)

version: 1
identity:
    hostname: test
    username: tester
    password: an_encrypted_password

Installer error:

 2021-08-05 13:03:52,379 DEBUG root:39 start: subiquity/Filesystem/apply_autoinstall_config/convert_autoinstall_config: 
 2021-08-05 13:03:52,379 DEBUG subiquity.server.controller.filesystem:193 self.ai_data = {'layout': {'match': {'path': '/dev/sda'}, 'name': 'lvm'}}
 2021-08-05 13:03:52,379 DEBUG subiquity.common.filesystem:369 bootloader Bootloader.BIOS
 2021-08-05 13:03:52,381 ERROR root:39 finish: subiquity/Filesystem/apply_autoinstall_config/convert_autoinstall_config: FAIL: max() arg is an empty sequence
 2021-08-05 13:03:52,382 ERROR root:39 finish: subiquity/Filesystem/apply_autoinstall_config: FAIL: max() arg is an empty sequence
 2021-08-05 13:03:52,382 ERROR root:39 finish: subiquity/apply_autoinstall_config: FAIL: max() arg is an empty sequence
 2021-08-05 13:03:52,382 ERROR subiquity.server.server:261 top level error
 Traceback (most recent call last):
   File "/snap/subiquity/2280/lib/python3.6/site-packages/subiquity/server/server.py", line 365, in start
     await self.apply_autoinstall_config()
   File "/snap/subiquity/2280/lib/python3.6/site-packages/subiquitycore/context.py", line 148, in decorated_async
     return await meth(self, **kw)
   File "/snap/subiquity/2280/lib/python3.6/site-packages/subiquity/server/server.py", line 310, in apply_autoinstall_config
     await controller.apply_autoinstall_config()
   File "/snap/subiquity/2280/lib/python3.6/site-packages/subiquitycore/context.py", line 148, in decorated_async
     return await meth(self, **kw)
   File "/snap/subiquity/2280/lib/python3.6/site-packages/subiquity/server/controllers/filesystem.py", line 103, in apply_autoinstall_config
     self.convert_autoinstall_config(context=context)
   File "/snap/subiquity/2280/lib/python3.6/site-packages/subiquitycore/context.py", line 142, in decorated_sync
     return meth(self, **kw)
   File "/snap/subiquity/2280/lib/python3.6/site-packages/subiquity/server/controllers/filesystem.py", line 200, in convert_autoinstall_config
     meth(disk)
   File "/snap/subiquity/2280/lib/python3.6/site-packages/subiquity/common/filesystem.py", line 389, in guided_lvm
     self.add_boot_disk(disk)
   File "/snap/subiquity/2280/lib/python3.6/site-packages/subiquity/common/filesystem.py", line 372, in add_boot_disk
     new_boot_disk.partitions(), key=lambda p: p.size)
 ValueError: max() arg is an empty sequence