Unable to import pool - Pool not found.

I am having trouble importing a pool from Truenas Core in to Truenas Scale 21.02-ALPHA.1

The error message I get is:
[ENOENT] Pool 2491833529097242126 not found.

At commandline "zpool import 2491833529097242126" works fine.

Another pool from the same Truenas Core machine imported without issues.

The full error message is:

Error: concurrent.futures.process._RemoteTraceback:
"""
Traceback (most recent call last):
File "/usr/lib/python3.9/concurrent/futures/process.py", line 243, in _process_worker
r = call_item.fn(*call_item.args, **call_item.kwargs)
File "/usr/lib/python3/dist-packages/middlewared/worker.py", line 94, in main_worker
res = MIDDLEWARE._run(*call_args)
File "/usr/lib/python3/dist-packages/middlewared/worker.py", line 45, in _run
return self._call(name, serviceobj, methodobj, args, job=job)
File "/usr/lib/python3/dist-packages/middlewared/worker.py", line 39, in _call
return methodobj(*params)
File "/usr/lib/python3/dist-packages/middlewared/worker.py", line 39, in _call
return methodobj(*params)
File "/usr/lib/python3/dist-packages/middlewared/schema.py", line 1003, in nf
return f(*args, **kwargs)
File "/usr/lib/python3/dist-packages/middlewared/plugins/zfs.py", line 388, in import_pool
self.logger.error(
File "libzfs.pyx", line 391, in libzfs.ZFS._exit_
File "/usr/lib/python3/dist-packages/middlewared/plugins/zfs.py", line 379, in import_pool
raise CallError(f'Pool {name_or_guid} not found.', errno.ENOENT)
middlewared.service_exception.CallError: [ENOENT] Pool 2491833529097242126 not found.
"""

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
File "/usr/lib/python3/dist-packages/middlewared/job.py", line 378, in run
await self.future
File "/usr/lib/python3/dist-packages/middlewared/job.py", line 414, in __run_body
rv = await self.method(*([self] + args))
File "/usr/lib/python3/dist-packages/middlewared/schema.py", line 999, in nf
return await f(*args, **kwargs)
File "/usr/lib/python3/dist-packages/middlewared/plugins/pool.py", line 1420, in import_pool
await self.middleware.call('zfs.pool.import_pool', pool['guid'], {
File "/usr/lib/python3/dist-packages/middlewared/main.py", line 1266, in call
return await self._call(
File "/usr/lib/python3/dist-packages/middlewared/main.py", line 1231, in _call
return await self._call_worker(name, *prepared_call.args)
File "/usr/lib/python3/dist-packages/middlewared/main.py", line 1237, in _call_worker
return await self.run_in_proc(main_worker, name, args, job)
File "/usr/lib/python3/dist-packages/middlewared/main.py", line 1164, in run_in_proc
return await self.run_in_executor(self.__procpool, method, *args, **kwargs)
File "/usr/lib/python3/dist-packages/middlewared/main.py", line 1138, in run_in_executor
return await loop.run_in_executor(pool, functools.partial(method, *args, **kwargs))
middlewared.service_exception.CallError: [ENOENT] Pool 2491833529097242126 not found.