Ok farmer here so The rubbery nature :
The atta u buying is from wheat which got rain right before it got harvested, atta although perfectly ok roti will not come out good , just rubbery.
If u changed the atta, than ur making roti too thick, and tawa also needs to be good quality and very clean, scrap it properly.
Start making roti very thin, it will burn out 1st try , so gradually make it thicker, until u know the right thickness to make it cooked uniformly.
Use a cloth and very gently press on roti on tawa to make the contact with tawa uniform.
Just 2-3 flipping of roti is more than enough, if ur doing more than that ,ur not letting roti to cook properly and hence rubbery.