Yes I think this is one of those questions that I and BA6501 have occasionally answered in the past, but no-one has come back to say "yes it happened" or "no it didn't"!

Regardless, I2 flights can be booked under IB code and these certainly count as eligible. The question is whether I2 Prime counts as eligible, I think it is eligible, but there is a valid argument for saying these flights are not eligible. Since I presume it's all processed via IB's IT it seems to come out in the wash as being IB and therefore no problem.