Can't select Audio DSP Filter

I can’t select Audio Filter, it just won’t stick. If I remember correctly this bug appeared in 1.6.3 or somewhere around that. Please check this out.

EDIT:
The reason I use audio filter is to add high shelving to cut some of the high content to make retroarch sound more like the hardware console.
Kega Fusion has built in Lowpass filter to sound like the Model1 Genesis console, but Genesis Plus GX lacks this feature and sounds shrill.

This issue should be fixed now in 1.6.9.