Weird case of the software letting the hardware down. You did the hard part guys!
What's annoying is you have to do it in three steps: first transfer it to the app's internal storage, and then save it out to actual files, then delete the internal storage; and you need 2x the disk space.
(Another annoying thing is in some countries they just disable the 5 GHz WiFi, so transfers end up taking forever. Very annoying when traveling, and if I lived in one of those countries I would have definitely returned it)