I recently flew HOU-DFW-MRY on a paid domestic first (I Fare Code) itinerary with AA. The HOU-DFW segment posted properly to my account, awarding 40 Tier Points. The DFW-MRY segment awarded 0 Tier Points:
I called BA to inquire about this, and was told that BA.com's Avios/Tier Points calculator shows that this route is ineligible for tier points. I double-checked, and that is in fact what the website shows:
The phone agent is not empowered to deviate from what the website shows, and fed me some line about this being an ineligible codeshare, because the flight was operated by Mesa Airlines on behalf of American Eagle. I found this a bit ironic, as the HOU-DFW segment that credited properly was operated by the very same aircraft and crew that subsequently operated DFW-MRY (N248LR). Pretty sure that's the first time in more than a hundred lifetime DFW connections that I've been fortunate enough to not have to change gates for a connection. Not even sure how to escalate this at this point, as phone agents imbue the website with something approaching the aura of papal infallibility. I would have booked an equivalent fare into nearby SJC if I knew BA would not award tier points for DFW-MRY.