Wavelab / VST setBusArrangements

There’s a particular workflow a client uses in Wavelab, where they create an empty project, add our plugin, then load an audio file.
This triggers this assertion in juce-VST3-Wrapper.cpp - 3267

    tresult PLUGIN_API setBusArrangements (Vst::SpeakerArrangement* inputs, Steinberg::int32 numIns,
                                           Vst::SpeakerArrangement* outputs, Steinberg::int32 numOuts) override
        if (active)
            // The host is misbehaving! The plugin must be deactivated before setting new arrangements.

An error message appears in Wavelab, then it deactivates the plugin.

Is there anything we can do in our code to avoid this?