However, currently, there is a logged issue that when using FileManager the Upload events are not exposed in wrappers settings and can not be handled. Below you will find a link to the logged issue in our official GitHub repo. As you will see in the link, there is a milestone set and the fix of the issue should be available with the next Service Pack. In the meantime, you could use the workaround suggested in the issue.
I hope you will find the provided information helpful.
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