Admittedly, I'm new to BIAB for Mac, but this seems to be something inherent in the program.
I've programmed a simple song in Chord Sheet Mode and added Coda and Segno signs
appropriately. The song plays the pattern properly but...after the DS al Coda, the chords played
are wrong. The song follows the pattern (# of bars) properly, but the chords are wrong.
So that's the first problem.

Secondly, when I change from Chord Sheet to Notation, none of the notation from the Chord
Sheet shows up. When printing out the Notation, there are no indications of any Codas, DS al Coda,
or anything other than the chord name and the occasional bar # for that matter.

How do I get the codas and related markings for repeats and "go to's" to show up in Notation mode
so that I can print a usable lead sheet?

One known (and reported) problem is that if you use repeats (not 1st, 2nd ending) and put a DS al coda on the last bar of the repeat it will not show up.

Presuming your underlying song is correct (linear) it will play, but the DS doesn't print. It's been around since fake sheet was introduced - about 2004, I think