The probe is on the glass reading °87.If the snake is not going by the UTH then it is too warm for him and he heads to the cooler side. This is why you have a UTH and thermostat, so the 85° on the warm side will gradiate down to about 75° and he can choose where he wants to be.
What do you have the thermostat set to?
As far as lights go, I am an opponent. Too many risk factors.
The uth is barely warm to the touch��. .