Serum parameters can't be set

[manazoid]

@psobot What I do wrong?

I open serum vst3 in pedalboard and would like to change 'mastervol' parameter. I can read it:

{
  "mastervol": {
    "range": [
      null,
      null,
      null
    ],
    "is_discrete": true,
    "is_boolean": false,
    "num_steps": 2147483647,
    "raw_value": 0.699999988079071,
    "string_value": " 70% (-9.3 dB)"
  }

But I can't change, but my usual DAW (studio one) support it.

from pedalboard import load_plugin

serum_path = r"C:\Program Files\Common Files\VST3\Xfer\Serum.vst3\Contents\x86_64-win\Serum.vst3"
synth_plugin = load_plugin(serum_path)

synth_plugin.mastervol = 1.0

print("Showing synth GUI..")
synth_plugin.show_editor()  #no changes at gui

I already tried:

1. synth_plugin = load_plugin(plugin_serum_path, parameter_values={'mastervol': ' 46% (-20.2 dB)'}) # predefine on load
2. synth_plugin.__setattr__('mastervol', ' 2% (-97.2 dB)')
3. synth_plugin['mastervol'].raw_value = 1.0
4. synth_plugin.parameters['mastervol'].raw_value = 0.46 # ' 46% (-20.2 dB)'
5. synth_plugin.parameters['mastervol'].raw_value =' 46% (-20.2 dB)'

Nothing changes