The general rule is that if the marketing airline/booking class combination doesn't appear in the ba.com tables, you should assume it earns nothing.

This rule has operated in the past in relation to some long-haul business class booking classes. Understandably, people were disappointed when they paid not insubstantial amounts of money for a long-haul business class ticket and then found it earned precisely zero in BAEC - but that was the situation.

So it would not be a surprise to find that the same rule operated here, even though the cabin concerned is premium economy.

It's also worth remembering that if the flight earns nothing in BAEC, it will not count as one of your two/four qualifying flights for status even if it otherwise satisfies the rule about qualifying flights.