AU Validation Failed - Retaining parameters' value

My plug-in is failing AU Validation through auvaltool with the following error:

Testing that parameters retain value across reset and initialization
ParameterID=98116753, Scope=0, Element=0: Saved Value = 0.943359, Current Value 0.500000
ParameterID=98116759, Scope=0, Element=0: Saved Value = 0.900391, Current Value 0.500000
ERROR: Parameter did not retain set value when Initialized

* * FAIL

The parameters in question are gain parameters which pass the check a few lines above in auvaltool:

Parameter ID:98116753
Name: Filter 1 - Gain
Parameter Type: Generic
Values: Minimum = -27.00, Default = 0.00, Maximum = 27.0
Flags: Values Have Strings, High Resolution, Can Ramp, Readable, Writable 
  -parameter PASS

...

Parameter ID:98116759
Name: Filter 7 - Gain
Parameter Type: Generic
Values: Minimum = -27.00, Default = 0.00, Maximum = 27.0
Flags: Values Have Strings, High Resolution, Can Ramp, Readable, Writable 
  -parameter PASS

Only these two parameters are showing the error even though, as you can tell by their names, they are just 2 of 7 identical gain parameters.
The parameters are created like so (in a for-loop):

auto gain = std::make_unique<ParamFloat>("gain" + String(i),
                                         groupName + " - Gain",
                                         NormalisableRange<float>(-globals::gainRange,
                                                                  globals::gainRange),
                                         0.f,
                                         String(),
                                         AudioProcessorParameter::genericParameter,
                                         [](float value, int) -> String
                                         {
                                             int dp = 2;

                                             if (value >= 10.f)
                                                 dp = 1;

                                             return String(value, dp);
                                         },
                                         [](const String& text) -> float
                                         {
                                             return text.getFloatValue();
                                         });

Then added to a group which is in turn added to the AudioProcessorValueTreeState using this method:


The parameter values are set in the setStateInformation() in the usual way:

void PluginProcessor::setStateInformation (const void* data, int sizeInBytes)
{
    std::unique_ptr<XmlElement> xml(getXmlFromBinary(data, sizeInBytes));

    if (xml.get() != nullptr)
        if (xml->hasTagName(apvts.state.getType()))
            apvts.replaceState(ValueTree::fromXml(*xml));

    // ...
}

I’ve run auvaltool in debug and put a breakpoint in setStateInformation() but it doesn’t seem to be called during this test that’s failing!

Any help with this would be greatly appreciated, thanks!

What does your getStateInformation function look like?