Denoiser execution error

I’m trying to speed up the viewport raytracing with cycles, so that my computer isn’t working on the render longer than it needs to. The denoiser is incredible! Currently I’m using the NVIDIA denoiser plugin with Quadro P4200 video card.

In doing this, I’m running into an issue when the samples are too low then the denoiser doesn’t work and it says “Denoiser execution error.” under the information tab.

It depends on the size of the scene, for example this scene needs minimum 30. Is there a way to force the denoiser to work even with very low samples?

One other weird thing, I’m only able to successfully control the sample count by directly clicking on it in the view port. Didn’t see this in any manual, just more or less found it by trial and error - I could have missed it though.denoisertest.3dm (506.0 KB)

sample file:
denoisertest.3dm (506.0 KB)

@DavidEranen , @andy here a case where post effects should be applied at least to the last frame in the viewport, since this can fall within the current time steps.