Cannot add cache disk to existing pool

After upgrade from 11.3 to TrueNAS 12 Beta 1, I had removed a cache disk from my pool to be used elsewhere.   I later tried to add the disk back into the pool as an L2 Cache, however I get an error which is still present on Beta 2.  The pool is encrypted with the legacy encryption.  The SSD which I'm attempting to add was wiped completely after it was removed from the pool.

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Error: Traceback (most recent call last):
  File "/usr/local/lib/python3.8/site-packages/middlewared/job.py", line 361, in run
    await self.future
  File "/usr/local/lib/python3.8/site-packages/middlewared/job.py", line 397, in __run_body
    rv = await self.method(*([self] + args))
  File "/usr/local/lib/python3.8/site-packages/middlewared/schema.py", line 973, in nf
    return await f(*args, **kwargs)
  File "/usr/local/lib/python3.8/site-packages/middlewared/plugins/pool.py", line 797, in do_update
    enc_disks = await self.middleware.call('pool.format_disks', job, disks, {'enc_keypath': enc_keypath})
  File "/usr/local/lib/python3.8/site-packages/middlewared/main.py", line 1233, in call
    return await self._call(
  File "/usr/local/lib/python3.8/site-packages/middlewared/main.py", line 1191, in _call
    return await methodobj(*prepared_call.args)
  File "/usr/local/lib/python3.8/site-packages/middlewared/plugins/pool_/format_disks.py", line 56, in format_disks
    await asyncio_map(format_disk, disks.items(), limit=16)
  File "/usr/local/lib/python3.8/site-packages/middlewared/utils/asyncio_.py", line 16, in asyncio_map
    return await asyncio.gather(*futures)
  File "/usr/local/lib/python3.8/site-packages/middlewared/utils/asyncio_.py", line 13, in func
    return await real_func(arg)
  File "/usr/local/lib/python3.8/site-packages/middlewared/plugins/pool_/format_disks.py", line 42, in format_disk
    disk_encryption_options['passphrase_path']
KeyError: 'passphrase_path'

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