> The HDD is a Seagate 250GB 7200rpm, the SDD is a Samsung 250GB EVO 850.
> The total capacity matches exactly.
You mean they really have *exactly* the same number of blocs?
> dd if=/dev/sda of=/dev/sdb status=progress bs=4K
FWIW, after doing that, I'd recommend you look at the partition table,
edit it (ever so slightly) and save the result: GPT partition tables are
duplicated: one copied at the very beginning and one copy at the very
end, so if the drives don't have exactly the same size the secondary
copy will appear corrupted.
Sadly, I don't think that explains your problem,
Stefan
