Edited Issue: QuantizeSettings + AnyCPU = Specified cast is not valid [1223]

This code works in version 6.8.9.002-Q16-__x64__-net40 version:
var qSettings = new QuantizeSettings {Colors = 8, DitherMethod = DitherMethod.No};

However, when I switched to the __AnyCPU__ equivalent, it now tells me "Specified cast is not valid"

Any idea why that would be happening?