Hi @Benny1980, can you check if "Fast Charging" is enabled? You can do this via: Settings > Device Maintenance > Battery > 3 dots (top-right) > Advanced Settings > Toggle on "Fast Cable Charging" and if it is, please toggle the function off and then back on.
Next, make sure that the tablet's software is up to date for maximum stability and updated features: Settings > Software Update > Download and install. If you keep having issues, please try charging the tablet without the case/cover and do a Soft Reset by pressing and holding the Volume Down as well as the Power buttons for 10 seconds. Finally, make sure to be using an original Samsung charger and that you are charging the tablet from a power socket and not from a PC/laptop.