Can you try to manual edit the mixxx.cfg in C:\Users\%USER%\Application Data\Mixxx\
[Waveform] WaveformType from 6 to 2 (Software filtered) or 0 (empty)
In the original Bug Mixxx GUI is not displayed at all so this might be a different issue, but you can give it a try.
It is also helpful if you can provide the mixxx.log file.
Maybe it is the same issue like in Bug #1008999.
Can you try to manual edit the mixxx.cfg in C:\Users\ %USER%\ Application Data\Mixxx\
[Waveform] WaveformType from 6 to 2 (Software filtered) or 0 (empty)
In the original Bug Mixxx GUI is not displayed at all so this might be a different issue, but you can give it a try.
It is also helpful if you can provide the mixxx.log file.