Issue With Comb Filter At Low Frequency

download test

I think that a listen with headphones should suffice: when the comb filter frequency reaches about 0.02khz, it starts clicking and turning into a chorus effect. I don’t know if the second problem is a bug or it is normal for comb filters, but the first should be surely avoided

I think it is inevitable for automating this kind of effect at that frequency, but maybe it also has to do with your source material?