Watch where the failure happens.
If the robot reaches the dock area but misses the final alignment, focus on clearance and sensor/contact cleanliness. If it searches in the wrong room, focus on map and dock location.

Where does docking fail?
Does the S8 reach the correct dock area?
Watch whether it navigates to the right location before the final docking approach.
Still cannot dock?
If the dock is powered, correctly located and unobstructed but final alignment repeatedly fails, avoid opening the dock or sensor assemblies and use qualified service.
Roborock S8 manual
Roborock’s S8 manual says to clear obstacles around the dock and move the robot closer if it cannot return.
Open official S8 manual