Debbie, you might have done nothing wrong although the temperature you selected is lower than many people use.
Often that rubbery texture you experienced is due to using what i call pumped chicken, frequently labelled as "seasoned". That's chicken that's been heavily injected with a brine solution and frozen. The solution causes the cells in the chicken to swell with water giving it that unpleasant texture.
Cafeterias and mediocre restaurants frequently use the product so they can cook a batch and hold hot for an extended period of time without it becoming too dry and stringy. You don't likely have that requirement at home.
To what internal temperature do you cook chicken breasts conventionally? Probably not 140F.
You might want to try either 150F, - or even 160F to get the usual restaurant-like texture. Two hours is long enough to SV cook at any temperature.