I am using CRFSuite for sequence classification (POS tagging). To my surprise it seems like CRFSuite does not like the label':' Units or tokens that have ':' as actual label are entirely skipped (no remark in the prediction output about a missing or skipped item)
I use other punctuation-related labels such as '.' or ',', but these are correctly used and outputted.
Has someone made a similar experience or nows why ':' is skipped ?