I finally got an answer from NCH. "MixPad and WavePad does not support VST3. Only 32-bit VSTs are supported by the software."
I had previously asked NCH support but did not get a direct answer. The MixPad user manual does not address the lack of VST 3. The WavPad User Manual is very clear stating that it only supports VST 2.
I hope this information helps.