Crash when converting camera image to PNG with "ConvertToPNG" on iOS

I’m developing an Augmented Reality app on iOS using UE4.27.2.

When I try to get a camera image with the “Get AR Texture” node
and convert it to a PNG image with the “Convert to PNG” node,
the application crashes.

I would appreciate it if you could tell me how to work properly.

UE ver.: 4.27.2
iOS ver. : 15.1
iPad Pro