I figured it out! Logically and not by fluke at all. My android phone had updated to Marshmallow 6.0 recently which is when all the problems started. My partner was happy because this meant he could adjust permissions to be a lot more strict, using a new feature allowing the user to choose which apps had which permissions, instead of always having all access and no choices. I put all this information into my head and yesterday figured that it was a permissions problem. My partner showed me where to find the options for this in the settings, not in the app as I had thought. As I suspected, the app had not been given permission to access my device files or camera. This is an awesome security feature, but I would have liked more information that the permissions had been turned off. So if you have the WordPress app on android, and keep getting the warning, media item could not be retrieved, try looking at your permissions.
I’m sorry for such a technical post, but I couldn’t find the answer online, so hopefully this helps out others.
This also means back to regular posting. Yay!