Just to let you know, as per your heading breadcrumbs, that Katalon Studio and Katalon Recorder are two separate applications. I think you are using the Web Recorder of KS.
There have been many requests on this forum to do with Salesforce, therefore, you should be able to find something. One of the first things you should check out is if there are any <iframe> around the Upload button. If there is, you have to switch to it first, and then carry on with your testing. For each <iframe> in your pathway, you have to do the same.