Just had am unusual situation. Maybe a glitch, maybe a new policy.
I booked economy return DUB-BKK having checked that upgrade seat were available on the LH legs. SH should then upgrade automatically.
Went to upgrade using points, system told me that the SH legs were not available for upgrade. I went ahead as it was HEL - BKK return I really cared about.
I went back in to the booking later and was able to upgrade the two SH legs using vouchers so the whole journey is now in business.
I'll call them tomorrow and see what they say.