Need help with an AABBB arrangement, please.

[nimbleswitch]

Yes this is a bit odd, but you have not used a closing repeat at the back of the 1st time ending which is what the player is expecting to see. I cannot remember ever seeing a 1st time ending without a closing repeat, they might exist but I am not sure they are very common because generally you can simply use repeats (unless it has a complicated form or nested repeats etc.)
So we did not check the behavior of the location of the double barline for this instance.

Just to make it clear to anyone else following this thread, here is a way to have the form, by changing where the opening repeat and segno are:
(I think this is what you would have done already Jack?)

BBB more correct - Borodin-Forrest-Wright

Hi, dflat-

I wonder if you noticed that your form suffers from the same quirk as mine? You inserted a double bar at the back of the 2nd Ending. But if you go in and remove that double bar and instead insert it from the front of the next measure (i.e., the Coda measure), when you play it back it goes straight to Coda and out — no repeats.

I guess the lesson is to make sure to insert the double bars at the end of a section, not at the beginning of the next section — at least in an Ending. Maybe in other instances as well, I dunno. Anyway, as long as we're careful to insert double bars at the end of the last measure in the section, either of our forms plays well in playback. It just becomes a matter of which form you prefer to see on the chart. I'm no musician or musicologist, so I don't really know, but I think I like the looks of yours better, for some reason.