If you operate the product with a low microstep resolution, the CW and CCW motion can give an a-symmetrical current wave / left and right turn different. This is because in low microstepping mode, the step size in the microstep table is increased.
Per default, TMC26x and TMC5031 ICs will not use the symmetrical points of the microstep table but just switch to a higher step size in the sine wave table. For symmetrical stepping, the distance from zero transition and maximum must be identical when coming from left side or right side.
To prepare for a symmetrical waveform, you need to position the drive to a fitting microstep position first, using 1/256 step. For 1/n microstep mode, please first do 128/n microsteps after IC power up, and then switch to 1/n resolution. With this, you get a symmetrical stepping. For halfstepping (1/2 microstep), this means, that you first do 64 microsteps.