Migration from CORE to SCALE fails with grub-probe error

I’m currently running TrueNAS core 13.3-RELEASE-p4, but since some apps that I use are hard to maintain on FreeBSD, I am looking to migrate to SCALE.
I tried to change the upgrade train, and to run the manual update, but unfortunately both methods fail with an error:

Error: Traceback (most recent call last):
  File "/usr/local/lib/python3.9/site-packages/middlewared/job.py", line 355, in run
    await self.future
  File "/usr/local/lib/python3.9/site-packages/middlewared/job.py", line 391, in __run_body
    rv = await self.method(*([self] + args))
  File "/usr/local/lib/python3.9/site-packages/middlewared/schema.py", line 981, in nf
    return await f(*args, **kwargs)
  File "/usr/local/lib/python3.9/site-packages/middlewared/plugins/update.py", line 389, in file
    await self.middleware.call('update.install_manual_impl', job, destfile, dest_extracted)
  File "/usr/local/lib/python3.9/site-packages/middlewared/main.py", line 1283, in call
    return await self._call(
  File "/usr/local/lib/python3.9/site-packages/middlewared/main.py", line 1251, in _call
    return await self.run_in_executor(prepared_call.executor, methodobj, *prepared_call.args)
  File "/usr/local/lib/python3.9/site-packages/middlewared/main.py", line 1156, in run_in_executor
    return await loop.run_in_executor(pool, functools.partial(method, *args, **kwargs))
  File "/usr/local/lib/python3.9/concurrent/futures/thread.py", line 58, in run
    result = self.fn(*self.args, **self.kwargs)
  File "/usr/local/lib/python3.9/site-packages/middlewared/plugins/update_/install_freebsd.py", line 66, in install_manual_impl
    return self._install_scale(job, path)
  File "/usr/local/lib/python3.9/site-packages/middlewared/plugins/update_/install_freebsd.py", line 86, in _install_scale
    return self.middleware.call_sync(
  File "/usr/local/lib/python3.9/site-packages/middlewared/main.py", line 1310, in call_sync
    return methodobj(*prepared_call.args)
  File "/usr/local/lib/python3.9/site-packages/middlewared/plugins/update_/install.py", line 69, in install_scale
    raise CallError(error)
middlewared.service_exception.CallError: [EFAULT] Command ['grub-probe', '--device', '/dev/ada3p2', '--target=fs_uuid'] failed with exit code 1: grub-probe: error: unknown filesystem.

These are my partitions in CORE;

% gpart show
=>      2048  1953523087  nvd0  GPT  (932G)
        2048  1953523080     1  freebsd-ufs  (932G)
  1953525128           7        - free -  (3.5K)

=>       40  234441568  ada0  GPT  (112G)
         40       1024     1  freebsd-boot  (512K)
       1064   33554432     3  freebsd-swap  (16G)
   33555496  200867840     2  freebsd-zfs  (96G)
  234423336      18272        - free -  (8.9M)

=>       40  234441568  ada3  GPT  (112G)
         40       1024     1  freebsd-boot  (512K)
       1064   33554432     3  freebsd-swap  (16G)
   33555496  200867840     2  freebsd-zfs  (96G)
  234423336      18272        - free -  (8.9M)

=>       40  976773088  ada1  GPT  (466G)
         40         88        - free -  (44K)
        128    4194304     1  freebsd-swap  (2.0G)
    4194432  972578696     2  freebsd-zfs  (464G)

=>       40  976773088  ada2  GPT  (466G)
         40         88        - free -  (44K)
        128    4194304     1  freebsd-swap  (2.0G)
    4194432  972578696     2  freebsd-zfs  (464G)

=>         40  19532873648  da0  GPT  (9.1T)
           40           88       - free -  (44K)
          128      4194304    1  freebsd-swap  (2.0G)
      4194432  19528679256    2  freebsd-zfs  (9.1T)

=>         40  19532873648  da3  GPT  (9.1T)
           40           88       - free -  (44K)
          128      4194304    1  freebsd-swap  (2.0G)
      4194432  19528679256    2  freebsd-zfs  (9.1T)

=>         40  19532873648  da2  GPT  (9.1T)
           40           88       - free -  (44K)
          128      4194304    1  freebsd-swap  (2.0G)
      4194432  19528679256    2  freebsd-zfs  (9.1T)

=>         40  19532873648  da1  GPT  (9.1T)
           40           88       - free -  (44K)
          128      4194304    1  freebsd-swap  (2.0G)
      4194432  19528679256    2  freebsd-zfs  (9.1T)

=>         40  19532873648  da5  GPT  (9.1T)
           40           88       - free -  (44K)
          128      4194304    1  freebsd-swap  (2.0G)
      4194432  19528679256    2  freebsd-zfs  (9.1T)

=>         40  19532873648  da4  GPT  (9.1T)
           40           88       - free -  (44K)
          128      4194304    1  freebsd-swap  (2.0G)
      4194432  19528679256    2  freebsd-zfs  (9.1T)

=>         40  19532873648  da6  GPT  (9.1T)
           40           88       - free -  (44K)
          128      4194304    1  freebsd-swap  (2.0G)
      4194432  19528679256    2  freebsd-zfs  (9.1T)

=>         40  19532873648  da7  GPT  (9.1T)
           40           88       - free -  (44K)
          128      4194304    1  freebsd-swap  (2.0G)
      4194432  19528679256    2  freebsd-zfs  (9.1T)

CORE is installed in ada0 and ada3:


% zpool status

...

  pool: freenas-boot
 state: ONLINE
  scan: scrub repaired 0B in 00:03:38 with 0 errors on Fri Sep 13 03:48:38 2024
config:

        NAME          STATE     READ WRITE CKSUM
        freenas-boot  ONLINE       0     0     0
          mirror-0    ONLINE       0     0     0
            ada3p2    ONLINE       0     0     0
            ada0p2    ONLINE       0     0     0

...

I wanted to confirm if maybe migration is not supported when TrueNAS is installed in a freebsd-zfs partition? Is there a workaround, or do I need a fresh install?