I am getting my feet wet with Game Maker Studio today. I miserably failed with the easiest of tasks: “Save a project. Restart the App. Load your project” … All the rooms I created (one actually) – was never loaded with an uninformative exception window. Luckily, when I tried to add just the room I learned that 10.5 is not a valid value. Of course its not as we use , (comma) as a decimal separator here in Poland.
While I failed to update Game Maker to accommodate for that change (seems it does not check regional settings and assumes a decimal separator is same globally) I managed to get things operational by making my Windows 8 machine to use . (dot) as the separator.
Lets see if I am used to , or I will manage this with a dot from now on.
PS. Sharing this as I failed to google for solution and hope others will find it so their time is not wasted.