I had the same trouble. For me, it was the power cable disconnecting slightly from the station. Since it connects upwards, it may have issues with gravity.
Please wipe the charging pad of the robot and the charging contacts at the bottom of the base station, place the robot correctly on the contacts in the base station for 2-3 hours, and observe. If it still cannot charge, please provide a video of the robot being charged in the base station. (Please contact: support.na@dreame.tech)