UWP: FileNotFound exception although the file exists

So, in my app I'm creating a file, where I would like to download content to. After I made some changes on the UI today, it throws an System.IO.FileNotFoundException right here.

FileList[FileCounter] = await ApplicationData.Current.LocalFolder.CreateFileAsync(name, CreationCollisionOption.ReplaceExisting);
//Creating the file

Debug.WriteLine(FileList[FileCounter].Path);
// This shows the right path - the file exists!

dlop = dl.CreateDownload(source, FileList[FileCounter]);
//Here the FileNotFound exception (Exception from HRESULT: 0x80070002) is thrown

When looking into the app's LocalFolder in the Windows Explorer, the file exists. As said, I left this piece of code totally untouched, so I have no clue why it suddenly doesn't work anymore.

If you need more material, please let me know! Thanks in advance.

UPDATE
As I found out, this happens only when I run the app in x86 mode. x64 and ARM work fine.