There's not reason why those wouldn't work, surely not on P3D 4.5, where the Render To Texture feature is surely supported. Check you haven't mistakenly disabled it in the Addon Manager settings.
Also, you don't say anything about your system, there are issues with RTT with PC with two graphic cards, including those that are part of some Intel CPUs, which should probably be disabled in the BIOS. Also, dual cards like SLI are not supported either.