Numeric Stepper adds "1" after the number, like 6 > 61


I have come across a weird problem with the NumericStepper component. Instead of for example changing number 6 to 7 when I press the up-arrow it changes into 61. And then 611, 6111 when i keep on going. If I leave the stepper and comes back to it, it works like it should.

Anyone who knows how to solve the problem?