Hey Charles,
Thanks for looking into it and reviewing the bug's assertion that this is an app developer "problem" - it really hit home how little the devs are considering this a bug. Ever since the bug was closed a few days ago, a bunch of people have replied telling them to re-open it because it isn't a dev problem, it's a mounting problem.
Since I really wanted this to perform exactly the same way it does on my phone, with no work-arounds that use the internal storage at all, I bit the bullet and did the dev mode/rootfs arc-sdcard.conf modification outlined on this
blogger post. The only thing I had to change was the mount point, since my sdcard is on /dev/mmcblk1p1 for some reason, not /dev/mmcblk1. You can run the "Mount" command in a crosh shell to check for your card's mount point.
Maybe someday ChromeOS will get updated with the same sdcard setup that Android has, but until then, I'll just use the hack. Thank you again
(also posting this in case anyone else has a similar setup - it only took about 20m, and most of the time was spent switching to dev mode and waiting for it to wipe)
Screenshot shows where the path wouldn't update from my phone's SD card to my Chromebook's, but now contains the new path from the arc-sdcard.conf modification. Works perfectly now!
