You need to break down your problem further to see where things are not working.
First, check if the upload works. Upload a file through the UI and check the storage path to see if the file is actually in there. If it is, you know your upload works. If not, there's something wrong with the upload.
For showing the logo (assuming upload works and the file is in the correct spot), you can dd the return values and manually check if that URL works in the browser. If it doesn't there's an issue with the logic for getting the correct URL.