To open the Visual Designer you have two possibilities:
In Open Designer in the Designer menu:
View attachment 163250
Or. in the Files Tab:
View attachment 163251
Then, what do you mean with
'I get a blank screen' ?
Is the Designer displayed, but without showing any layout ?
If yes, it means that you have more than one layout files and none is displayed. You need to select one.
If no, i cannot help, i have never had such a problem.