Hi Peter,
Is it in with the Tinkers hybrid?
I was thinking about how timid some of these BF's are if they wouldn't do best alone to start out with.
Something worth trying is to put cardboard on the front & back of the tank & view the fish from the side panel. It gives him more room to retreat back & could make them less skiddish. It gives the fish the feeling of a sense of depth to it's surroundings
Discus keepers used to do this to get the fish less skiddish & to be more bold at feeding time. Some times they would go to the extremes of covering all the sides & making just a small hole to view the fish.
Covering the panels might stop the pacing unsettled behavior also because they can't see beyond to continue to search for ways to get beyond the clear barrier.
Think about how fish react in a clear plastic bag versus if the bag has that black sleeve. The reactions are quite different. Being thrown in a strange new environment is bad enough, but to see somewhere to escape, they frantically try to break through.