I've also had the Restricted to Economy notification on a positioning flight to DUB.
Today, however, my seat reservation disappeared on a DUB-LCY - Mrs NWIFlyer and I were in 3A/3B, but now the Club Europe cabin only consists of two rows, both fully occupied so I can't select a seat. I'm assuming this will be fixed by July, but wouldn't it be a shame if they had to downgrade us on the day and pay us 75% compensation under EU261?
More to the point, what on earth is BA's IT and seat configuration doing this time? It surely can't be too hard to recognise you have more than four passengers in CE and they might want a seat each, can it?