Can features be discarded by the classifier?

[PKholyavin]

Hello!
I am using crfsuite to train models on my own datasets, and I am testing different sets of features (I have a lot of them). However, some of those features seem to have no effect on classification results: e.g. first I use set of features A and get an F1 = X, and then I use set A + B and get the same results, and this repeats on every train and test set I have (if it is any help, my data is various acoustic features of speech in two languages). My question is: is this normal, or is there a possibility that some of these features are somehow discarded by the model?
Thank you in advance!

[PKholyavin]

Update: I have checked attributes_, and these features are indeed not used. What could be the reason?
Update 2: found out I had NaN values in those sets. Apparently if there are any these features are discarded with no warning...