@tomekslesicki There's always hope...
In this case your impulse response was just too short, so the convolution engine refused to load it - it actually had nothing to do with the sample rate or frequency response (or at least not directly - with lower sample rates the impulse response was resampled to have less samples than the audio buffer size and this is where the engine thought to call it a day and just not load it).
It should be fixed now, but please check if this is the case - it's a very minimal effort fix :)
