I don’t see anything obvious in the information you’ve provided.
A few more clarification requests to better understand what’s going on.
Where was the source of the grbl 1.1h firmware?
Did your Eleksmaker work previously with grbl 1.1e firmware? I assume that was before swapping to Endurance laser module but please confirm.
Can you confirm that power modulation in general works? Test this by first enabling “Enable laser fire button” and “Laser on when framing” in Edit->Device Settings. Then go to Move window. You’ll need your safety goggles on for the next steps and potentially a sacrificial material under the laser. Push the Fire button. Then increase power % incrementally. Does the laser light get brighter and dimmer as you raise or lower power level? No need to really burn anything, just enough to see if power is modulated.
Next thing to check is to confirm that your wiring to the laser is correct. Can you take a series of photos showing the overall wiring and components going from your controller to the laser module, closeup of connector on laser module, closeup of connector on controller, and closeup of any intermediate components. Preferably you would show any labeled markers for the connector ports.