There are a few possibilities. 1. The dough may be too wet so you might need to adjust the water content down a little for your environment. 2. Or it might be that the cycle is too long.  If you do not use a gluten-free setting, then it is likely that it will be left to prove (rise) too long.  Without any gluten giving it structural support, gluten-free breads are a little more fragile and if left for too long, they can rise too much and then collapse. 3. Did you cut into it before it had fully cooled. This affects the structural integrity of the loaf which continues to firm up while cooling down.