Taking a normal photo with the OM 4, they're being saved under the .cache folder which is below DJI.mimo/Camera. I expected them to be stored in Camera, is there some post processing Mimo is supposed to do before it moves them or is this where they should be?

Try asking in the appropriate forum.  This is the Spark forum.  It doesn't need OM4.  Unless you know better.

Hmm, was reading the OM 4 forum and clicked new post. No idea how it got here, assuming this is the spark forum because that's one thing the software doesn't tell me reading this on a mobile phone.

So the photos are stored in the Mimo app and then when you go to app you can save all the pictures locally to the phone.

Hi. I am sorry for the trouble this has caused. With regards to this concern. May I know the model of the mobile device you are using please? Please keep us posted for further assistance. Thank you.