I have recently had the same issue with QR flying out of LHR to BAH via DOH. I am BAEC Silver (OW Sapphire). I had checked in using my QR FFP as I am registered for a double tier point promotion over Xmas and wish to get to Gold this coming year. At check I was advised that if i wanted to avail the OW Sapphire benefits i would have to collect BAEC miles on this flight as "the system does not allow this". As you have quite rightly stated their is no clarity on this issue anywhere on the Oneworld website. I have written to QR and await their response and will keep the forum updated