iPhone 6 Plus photos taken within a game crash the game app

I'm playing Sky: Children of the Light, and the latest Season includes a camera with various settings. I can use it in some areas of the game, where the shutter release clicks then I get icons asking whether to save it to Photos. 

It has to be used in a new area of the game. In that area, as soon as I touch the shutter release the app hangs for a couple of seconds then quits. 

I have requested help from the devs, but their reply was a rambling version of “We don't want to know“. They have a lot of crashes and other issues. 

Is there something the camera tries to do after taking the photo but before asking whether I want to save it, which might demand more or better resources than a 6 Plus can muster? Is there anything I can do to solve this?