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
machinedesign.com/…

(2) Step Motor Basics – GeckoDrive 2017nov03
geckodrive.com/support/…

(3) What is a chopper drive for a stepper motor? – Dantelle Collins, 2017aug11
linearmotiontips.com/…

(4) Optimized Current Control Chopper Modes – Trinamic

(see full text)

There you are – Chopper Mode (Ref 3).