Why does the RX1 AF struggle with this scene?
I only use flexible spot for up close shallow DOF work. I use center for stuff like this.
When I was doing my walk-about yesterday, I decided to take a shot of this building. I had spot focus on at the time (because I'd been taking shallow DOF shots where the subject was at the edge of the frame), but the focus point was now centred. However, with the focus point on the building itself, the camera took 3 or 4 tries to get a lock. I was very surprised. I don't think my other cameras (including RX100 or NEX7) would struggle so much. Sure, it was twilight, but it wasn't so dark. And the building facade seems to have a reasonable degree of contrast. I was quite surprised. [Yes, it's a boring and horrible shot].
Anyway, following Steve Huff's comments, I think I will stick to centre focus on this camera. It does seem snappier and more reliable.