I am using MaasLin2 to test the association between taxonomy and binary clinical outcomes. In the metadata clinical outcomes, I have several missing values (shown as “NA”). After I ran MaasLin2, the output file still showed the total number of samples, i.e., not removing samples with NA values. And in the box plot for showing significant taxonomy association, in addition to 0 and 1, there is another box for NA. It seems MaasLin2 can remove missing values automatically when performing association analysis, would you mind to let me know how to do that? Thank you.