Being present means to feel what you are feeling, see what you are seeing, hear what you are hearing, and taste what you are tasting. In other words, your mind is not somewhere else during these experiences. If your mind is not present you lose the actual experience you should be having, to one degree or another. It like when someone speaks to you and your mind is somewhere else and you don’t hear what they are saying, or when you read a book and your mind drifts and you don’t remember anything you read. Even though you are hearing or reading words you are not present to them.
In relation to chanting being present means to allow yourself to feel Kṛṣṇa in his holy name. Sometimes we try to feel the holy names rather than allow ourselves to feel what we are really feeling. In other words, we are not feeling what we are feeling at the moment. We are thinking of something else and thus not feeling the presence of Kṛṣṇa we would feel if we just allow ourselves to feel. In other words, feel the holy the name that you are feeling!
If you say you are not feeling anything, actually it is impossible to not feel anything. Allow yourself to feel the vibration of the holy name, to feel Kṛṣṇa’s mercy and love coming to you through the holy name. Open up to feeling. You don’t have to try to achieve anything; just receive and feel what is already there.