High pass Bi-quad Filter 0V Output

[Fire-wood]

If the High BQ Filter is connected up without touching the frequency or q knobs, the output of the filter is 0V. If the frequency is changed, even slightly, the output then acts as normal.

[cpdt]

To clarify, this only happens when the node is first created? Or it happens whenever the frequency/q are zero?

[Fire-wood]

I seem to get inconsistent results if the frequency knob is moved and then set back to 0. Sometimes it's ok, other times I get no output but oddly varying knob values (large negative numbers) and once I got crackling.