First thing to check is fluid level in the pump reservoir, driver side behind rear wheel inside trunk.
If low, then check real carefully for a hydraulic leak, there are 7 cylinders that can leak :
1 tonneau cover lift cylinder
1. tonneau cover latch cylinder
2 rear bow lift cylinders
1 rear bow lock cylinder
2 main top lift cylinders.

If ANY are leaking, probably best to have all rebuilt by tophydraulics.com for @ $700
( you have to remove and ship your cylinders )