NMF-QMV spectral unmixing with 2 endmembers

[meyerct1]

Hello,
Thanks for this wonderful function. I'm using to separate different fluorophores from microscopy images. However, if I only want to separate 2 endmembers (i.e. p=2) I get the following error:

I think this is due to the dimensionality reduction step in the NMF-QMV function:

Any suggestions on how to handle this case?
Thanks again