Expedia "Up to 12X Miles" - Capital One Offers

I'm getting ready to book a flight and I'm wondering if anyone here has taken advantage of the Expedia "Up to 12X Miles" offer on Capital One Offers? Booking through Capital One's Portal will get me 5X miles. Is there any way to know if I'll get 5X or more miles by booking the flight through Expedia?

For reference it's about $1300, so it's 6500 miles (5X) vs 15,600 miles (12X). In addition I'd earn OneKey Cash booking through Expedia. Ever little bit helps.

I feel like I should just go ahead with it. I have no issues booking with Expedia. But I figured I'd ask here to see if anyone has had any issues or didn't receive the miles promised in the past. Also, if there's any way to know what I'll earn, the wording "up to 12X" is a bit misleading. Will I earn 1X or 12X?

Thanks in advance!