Why are the elements of my scrollview scaled different after refreshing?

Hey,

I followed the official tutorial for building a scrollview. (https://unity3d.com/de/learn/tutorials/topics/user-interface-ui/intro-and-setup?playlist=17111)

Now I'm facing a problem if I call the RefreshDisplay().

These are the settings of my Content:




If I run the scene the first time everything looks fine like this (RefreshDisplay() is called the first time):




Then if I call RefreshDisplay() again, the items of the ScrollView are scaled like this:




For the rows/items of the list I use a prefab, which has a Layout Element with Min Height checked and set to 40. (This row element has four subelements as you can see on the "first-run screen": date-label, button1, ":"-label, button2)