I recently made chicken pot pie, but the dough sinks into the filling leaving a soggy, ugly crust. Any reason why this is happening and Suggestions?

Sounds like you put your crust on your filling when it was still warm. That melts the pastry and makes it gooey. Always use a cold filling to put your pies together.

chicken pot pie with savory crumble topping. i want to make, but haven't so far, the chicken pot pie by american's test kitchen. probably not what you are wanting but maybe for another day.

Did you cut slits in the top? Once I forgot to do that and the top crust sunk.

Is your filling nice and hot? If not, it can lead to dough disaster (she says wincing at memories of failed chicken pot pie attempts). Other than that, I would wonder if the oven temperature is high enough for the dough you're using. There are plenty of awesome bakers on this site who could probably speak to this better than I (looking at you, AntoniaJames!)

I make a version of this a lot and I have firmly come to believe that it turns out better when I use my fav biscuit recipe on top instead of pie dough. As long as your filling is piping hot, you can cook it at the same temperature and time as your preferred biscuit recipe. Plus, you get a thicker layer of carbs on top - yah carbs! Good luck and godspeed!