Roy Smith wrote:

Eventually the controller told me I could turn back inbound and
descend to 2900. I did so and found myself tracking inbound, but with
the CDI giving me indications opposite of what it should have been,
apparently the box thinking I was still trying to track outbound. I
could see (from the moving map) that I was south of the final approach
course, but the CDI was giving me "fly left" indication. At some
point, while we were puzzling over this, the CDI suddenly flipped to
"fly right"; I think this might have been as we passed CFGUY inbound.
Everything proceeded normally from that point.

Another option at this point would have been to select VTF (Vectors to Final). When it became clear the
box was still stuck on the outbound leg or PT, this would have cleaned up the flight plan and made the
inbound leg to the FAF active. The CDI would then indicate normal deviation to the inbound course also.

Mike