This code has worked before but doesn't work anymore. It is the first time I tried it after the ImageRTPtr change.

Hello, ImageRTPtr is reference counted so you need to keep a valid reference to it.

ImageRTPtr rt=D.fxEnd();

Also exporting to TGA currently is supported only for DX9.

Exporting to TGA will be available on all platforms in next release.

Thanks, it's working now, but the backbuffer rendering handling is a bit different now. Before I could do twice such calls in one function, but it was crashing. After separating the calls it worked. I'm only using this to aggregate things onto a large texture to be used in the game, so it's ok.