Where did it go wrong? I re-read it from the beginning and then I spotted it: Right from the start the characters were 'dancing' for me. I am a good wordsmith and I can make them do what I want them to do, but they were kind of behaving like performing monkeys: jumping through the hoops I'd set up for them. So the chapter could pass as decent prose but in all honestly, I had been flippant with my characters. I hadn't listened to their needs. I hadn't done them justice.
I decided to slow right down and dig deep. How were these guys feeling? And how might that manifest itself? What had each of them been doing ten minutes earlier in the plot? And what if I took the narrative back ten minutes to just before the two characters met up? I tried it, and it let them breathe a little more easily, plus it helped me feel my way into their lives - properly - and they appreciated it. They stopped behaving like my puppets and came to life. Oh, the relief!
I hereby apologise to my characters: Dear Steven and Annie - I'm sorry for not really listening to you. I was a badly behaved writer - you are great characters and I will pay more attention to you in future.
WRITING TIP: Characters not ringing true? Take it back a few minutes and see how your characters react.