Motorcycle Questions? Ask a Mechanic.
It certainly could be ABS related.
The easiest way to tell is to disconnect the line from the master cylinder and push the pedal. If the pedal operates normally and you know the caliper pistons are free then the problem is most likely in the ABS motor.
There can be difficulty with air entering the ABS system that cannot be bled out. Back before I had a computer capable of operating the ABS motor I used to crack the banjo on top of the ABS motor to bleed a particular line before the air makes it into the ABS motor.
If all this doesn't work then you don't have many options other than finding a shop with a computer than can test operate the ABS motor to verify it is working properly.
I hope this helps. Please let me know if I can be of further assistance. Thanks, P.J.