I heard there are many reasons this could happen:
- oven temp too hot.
- defective recipe.
- opening oven before the cake is set.
- overbeating the batter.
- also, u might need to insert a toothpick all over, especially the middle to check for readiness.
How big is the tin you're using? Also, do you check the centre with a toothpick first?
I am having the same problem but I think is the pan. I have a set of Wilton and Magic Line and i have on several ocassions baked my red velvet with the batter split between both, same amount of batter(weighed), baking strips on both and yet, the Wilton bakes up nice and even, Magic line does not rise as much and it sinks in the middle. I have let the batter cook longer, lower the temp to 325, instead of the normal 350 and nothing.