The problem is with the leaver or the master cylinder. (MC)
The callipers, discs & ABS should play no part in the return of the MC plunger/piston assembly.
The return spring in the MC should have enough force to have the leaver return to it's original position.
Over time the leaver and the pivot pin will wear down, have a good look at both it could be time to replace them, the hole in the leaver and the pin will become oval not round.
There is a rubber boot covering the MC plunger/piston where the leaver meets the plunger/piston, ensure it is in good condition and sliding well so as not to limit the plunger returning.
If you still have the problem there is a return fluid port in the MC, this is to allow the pressurised fluid to return to the MC when the you release the leaver, there could be crud built up and restricting the ports.
If you had a reason to change the fluid in the first place like poor brake performance it could all be linked back to the condition of the MC.
Some of the 19 rides in my shed
2014 V2, Snoopy
2009 Wee, Pumbaa the pig
WR450F, The Blue Postie Bike
YZ250N smoker with rego, Stinky.
Yamaha MT09 (FZ09), The Scud missile.
Club Lead not Club Med.
He with the most toys wins.
Out of my depth in a puddle.
Live life on the edge you will see more that way.
Ridding a motorcycle keeps things in balance.
At the end of each trail and at the end of each day history is made.