Motor current sudden increase means stalled or jammed.
The other reason is that I am trying the driver in “chopper mode“, or constant current mode. You might skimmed that following references for a rough idea of “current chopping”.
(1) Misconceptions about Stepper Motors Explained – MachineDesign 2017feb18
(2) Step Motor Basics – GeckoDrive 2017nov03
(3) What is a chopper drive for a stepper motor? – Dantelle Collins, 2017aug11
(4) Optimized Current Control Chopper Modes – Trinamic
There you are – Chopper Mode (Ref 3).