I have a very bad bug with DrawMaterialToRenderTarget function in UE 4.22. It not draws anything to render target on Android build.
I take hit result under finger by channel, make simple line trace according to it, and pass all this as point damage to hit actor.
In hit actor I get collision UVs from hit, and pass them as coordinate to my material.
All of this works in editor and in game. I can draw on plane mesh with it and everything is fine.
But after update to UE 4.22 (with android works R7) it won’t work in development or shipping packaged build on devices.
Initially I had similar problem with previous UE4 versions, but after I set render target format to RTF_RGBA8 everything fixed.
For now I tried to package with ALL render target formats and nothing.
I didn’t find any problem in line trace or find collision UVs logic.
I also tried to switch to “draw canvas to render target” flow, and it also works in editor, but not on device.