hi again ...
i delved a bit deeper myself, as you provide very little information
the version you used is 1.37 and it has a little bug. (which is fixed in the latest version, currently 1.39)
i still do not fully understand why you need a 8 step sequence to make the stepper run. the original stepper library manages to do so nicely with 4 step sequence. I am going to investigate further, and I will let you know.
just as part as my learning process, to really understand how steppers work, and how this library can be used