DataSource.Error: An IO error occurred while trying to access the file...

I'm trying to create a variable query that outputs the name of the file most recently modified in a certain folder. I actually accomplished this yesterday and the output was successful, but when I refreshed the query today I received the following error:

DataSource.Error: An IO error occurred while trying to access the file 'FilePath'.

Details:

     FilePath

Code:

let
    //Choose folder
    Source = Folder.Files("\\xxx-my.sharepoint.com\personal\xxx\xxx\xxx\xxx\xxx\"),
    //filter out all but Excel files
    #"Filtered Rows" = Table.SelectRows(Source, each ([Extension] = ".xlsx")),
    //sort in descending order by date modified
    #"Sorted Rows" = Table.Sort(#"Filtered Rows",{{"Date modified", Order.Descending}}),
    output = #"Sorted Rows"{0}[Name]
in
    output

Again, this was actually working yesterday. I still have complete access to the network folder that is trying to be accessed, so I don't think it's a permissions issue.

Any ideas?