I can't think of any reason. Does this happen with my code too? Do you still get the NA's, while I get expected output?
Can you please post your code and sample data (the observations corresponding to which you have observations on all the columns) in form of a reproducible example? Noting the exact errors you're facing, some of us may get an idea about the problem.
If you don't know how to make a reprex, here's a great post: