macOS: battery doesn`t charge.

I have no issues here. It might be your mac's battery. Click on your battery icon, and option button at the same time, it will tell you the state of the battery. See what it says. Also check you have power from your socket, try it in a new place or a different device to see if the socket works.

I have a marginal power supply, apparrently. Even on El Capitan when the battery was down around 60% or lower, not sure of the exact point where it happened, but it would flicker between charging and not charging. With macOS 10.12 on the same hardware and same power supply it goes into a longer "Not Charging" period, with a brief attempt to charge and then it stops again. So I suspect Apple is definitely changing something in this area. I have another power supply that when plugged into the same computer has no problems. I'm assume that you have already done it, but it might be worth looking into resetting PRAM and/or SMC.

I had the same issue here on my Macbook pro, I go to put it onto the charger with about 45% left on the battery and it said not charging, I kept on pluging it in, still said not charging. I managed to fix it just by turning the computer off then back on again. Not sure if that will work for you but it did for me.