"User was not authorized" using RelativePath option of Web.Contents() for excel files on Sharepoint

I am building a Power BI report that needs to be published to web with automatic refreshes. The report I am building pulls data from 10 excel documents, all located in separate document libraries on sharepoint online. Each excel document has 10 tabs, each with 2 named ranges that I need to pull data from - so that would result in about (10 documents) * (10 tabs) * (2 ranges) = 200 queries to pull all data in manually. Clearly a no-no.

I created a couple functions that would allow me to use a dynamic query to get all this data with only a few queries - the code for one of those functions is below:

(Location as text, Period as number) as table =>
let
	location_trimmed = Text.Remove(Location, {".", " "}),
	Source = SharePoint.Files("https://xxxxxx.sharepoint.com/teams/teamOne/" & location_trimmed, [ApiVersion = 15]),
	#"File Name" = location_trimmed & "MillScorecard.xlsx",
	#"MillScorecard" = Source{[Name=#"File Name",#"Folder Path"="https://xxxxxx.sharepoint.com/teams/teamOne/" & location_trimmed & "/Shared Documents/"]}[Content],
	#"Imported Excel" = Excel.Workbook(#"MillScorecard"),
	#"Range Name" = "Period " & Number.ToText(Period) & "!P" & Number.ToText(Period) & "_All_data",
	All_data_DefinedName = #"Imported Excel"{[Item=("Period " & Number.ToText(Period) & "!P" & Number.ToText(Period) & "_All_data") ,Kind="DefinedName"]}[Data]
in
	All_data_DefinedName

However, I soon found out that Power BI online doesn't support automatic refreshes for dynamic queries:

https://community.powerbi.com/t5/Service/Problem-with-automatic-refresh-data-source-not-supporting/td-p/24254

I found an article that used Web.Contents options as a hack get around this, so I figured I would give it a shot - using the RelativePath option, it seemed like I could get the same kind of hack done. 

https://blog.crossjoin.co.uk/2016/08/23/web-contents-m-functions-and-dataset-refresh-errors-in-power-bi/

My resulting code:

(Site as text, Location as text, Period as number) as table =>
let
    location_trimmed = Text.Remove(Location, {".", " "}),
    relative_url = Site & "/Shared Documents/" & location_trimmed & "MillScorecard.xlsx",
    url = "https://xxxxxx.sharepoint.com/teams/teamOne",
    Source = Excel.Workbook(Web.Contents(url, [RelativePath=relative_url]), null, true),
    #"Period 1!P1_All_data_DefinedName" = Source{[Item="Period 1!P1_All_data",Kind="DefinedName"]}[Data]
in
    #"Period 1!P1_All_data_DefinedName"

When I tried to invoke this function - after entering my SharePoint credentials - I get this error:



When I change the function to use the entire url as the base url in the Web.Contents() call, it works perfectly fine.

Is there any way I can get around this? Does anybody know of a better way to go about doing this??