subiquity probe_once fails with Invalid dep_id during 20.10 install

While performing an install to a zVM guest using the 20.10 iso from October 1, the subiquity installer reports:
   ┌────────────────────────────────────────────────────────────────────────┐
   │ │
   │ Sorry, there was a problem examining the storage devices on this ▴ │
   │ system. █ │
   │ █ │
   │ [ View full report ] █ │
   │ █ │
   │ If you want to help improve the installer, you can send an error █ │
   │ report. █ │
   │ █ │
   │ [ Send to Canonical ] █ │
   │ █ │
   │ You can continue and the installer will just present the disks █ │
   │ present in the system and not other block devices, or you may be █ │
   │ able to fix the issue by switching to a shell and reconfiguring the │
   │ system's block devices manually. │
   │ ▾ │
   │ │
   └────────────────────────────────────────────────────────────────────────┘

This happens just after enabling storage devices, from the installer ssh session. The inputs leading up to this failure on the SolutionsQA s5lp1-gen02 guest were:
  English
  dasd-eckd --> 0.0.0200 --> enable
  zfcp-host --> 0.0.f201 --> enable
  zfcp-host --> 0.0.f301 --> enable

Upon further inspection of the subiquity-debug.log (see attached) the following traceback is present:

2020-10-08 17:50:09,335 ERROR root:39 finish: subiquity/Filesystem/_probe/probe_once: FAIL: Invalid dep_id (partition-sda1) not in storage config
2020-10-08 17:50:09,336 ERROR block-discover:161 block probing failed restricted=False
Traceback (most recent call last):
  File "/snap/subiquity/2027/lib/python3.6/site-packages/subiquity/controllers/filesystem.py", line 154, in _probe
    await asyncio.wait_for(self._probe_once_task.task, 15.0)
  File "/snap/subiquity/2027/usr/lib/python3.6/asyncio/tasks.py", line 358, in wait_for
    return fut.result()
  File "/snap/subiquity/2027/lib/python3.6/site-packages/subiquitycore/context.py", line 142, in decorated_async
    return await meth(self, **kw)
  File "/snap/subiquity/2027/lib/python3.6/site-packages/subiquity/controllers/filesystem.py", line 135, in _probe_once
    self.model.load_probe_data(storage)
  File "/snap/subiquity/2027/lib/python3.6/site-packages/subiquity/models/filesystem.py", line 1633, in load_probe_data
    self.reset()
  File "/snap/subiquity/2027/lib/python3.6/site-packages/subiquity/models/filesystem.py", line 1351, in reset
    self._probe_data)["storage"]["config"]
  File "/snap/subiquity/2027/lib/python3.6/site-packages/curtin/storage_config.py", line 1348, in extract_storage_config
    tree = get_config_tree(cfg.get('id'), final_config)
  File "/snap/subiquity/2027/lib/python3.6/site-packages/curtin/storage_config.py", line 306, in get_config_tree
    for dep in find_item_dependencies(item, sconfig):
  File "/snap/subiquity/2027/lib/python3.6/site-packages/curtin/storage_config.py", line 276, in find_item_dependencies
    _validate_dep_type(item_id, dep_key, dep, config)
  File "/snap/subiquity/2027/lib/python3.6/site-packages/curtin/storage_config.py", line 224, in _validate_dep_type
    'Invalid dep_id (%s) not in storage config' % dep_id)
ValueError: Invalid dep_id (partition-sda1) not in storage config
2020-10-08 17:50:09,336 DEBUG subiquitycore.common.errorreport:375 generating crash report
2020-10-08 17:50:09,336 INFO subiquitycore.common.errorreport:393 saving crash report 'block probing crashed with ValueError' to /var/crash/1602179409.336369753.block_probe_fail.crash

The entire content of /var/log is attached, which includes the crash file mentioned just above.