Ok, here is a recording I made of all the crazy sounds I was able to make switching betwee Amp LFO at max + and -, and playing with filter cutoff, resonance, LFO rate, and brute factor. All oscillator shapes are at minimum for this entire thing.
I think this is normal, and I actually think it's kinda cool. I'm sure there will be a useful application for this. In the meantime, I would avoid the maximum - or + settings on the amp LFO.
Be warned, the dynamic range on the attached wave file goes from difficult to hear faint buzzing to very loud very bassy noise and back again. I would listen with low volume the first time.
https://soundcloud.com/clickplay/mbnowaves