Reward category question

[dgray]

I'm getting a problem where if a product is in more than one reward category and also a qualifying category it won't qualify for a reward. Here's my setup:

Reward promotion 1:
Qualifying category A contains products: a
Reward category B contains products: b, c, d

Reward promotion 2:
Qualifying category C contains products: b, c, d, e, f
Reward category is = Qualifying category C.

In promotion 2 if I add products b, c or d to my cart they don't qualify for rewards. If I add products e or f these do qualify for a reward. Promotion 2 is a buy one get one free promotion. If I remove a product from category B then it starts to qualify ok in promotion 2.

Is this a bug or is there a rule I'm not following? I'm using shopsite 8.0.1