I think so. I had a go on LGW to AMS and I could see HBO all the way to the final page (£38.79 in that case). Then I tried tried "Find Our Cheapest Fares" to see if HBO is available on a random route (OK, I'm cheating, it was actually SKG). So the cheapest fare on the headline figure is £59. It's available on 21 September. I click HBO on the 3 options (HBO, ET, CE). Next screen it magically goes to £74.79 and includes checked bags. Go back and the button falls into the ET not HBO column.

I've long had this unscientific view that BA.com goes a bit sick in the European evening, when the US Chase folk are hammering the system for all its worth. By the morning it often seems better / faster / more reliable. If you're not desperate, I'd leave it a day or two.