Braised short ribs differ in texture when on stove top vs in oven
"For the same time" seems to be your problem here. An oven will warm a pot much more slowly than a stovetop, especially a heavy iron stew pot. You'll need to monitor your temperature, and only count the time after it reaches 68 Celsius. The warming up phase can be easily close to an hour in the stove, eating away a lot of the actual cooking time.