Error: Source is accessing data sources that have privacy levels which cannot be used together.

I have a datasource that works fine in Power BI Desktop/Power Query. However, when publish to the service and try to refresh it from there, I get the following error: 

Data source error[Unable to combine data] Section1/Query1/u_Source is accessing data sources that have privacy levels which cannot be used together. Please rebuild this data combination.. The exception was raised by the IDataReader interface. Please review the error message and provider documentation for further information and corrective action. Table: Query1.

In this Power BI report, Query1 is the only datasource and is pseudocoded below, just to illustrate the structure:

let 
    _auth = 
        let
			//*** Bunch of code to call an authentication API and return a bearer token ***
            Source=DataRecord,
            token = Source[token] 
        in
            token,

    _get_json = (offset as number, limit as number, direction as text, year as number, month as number) as list =>
        let
			//*** Bunch of code to call an API using the bearer token from _auth 
			//    for a particular date period, page through results, and consolidate ***
            Source = Json.Document(Response)
        in 
            Source,
    
    _cm = 
		let
			//*** Bunch of code to call _get_json for the current month ***
			#"cm_Changed Type" = Table.TransformColumnTypes(cm_Table,{{"total", Int64.Type}})
		in
			#"cm_Changed Type",

    _lm = 
		let
			//*** Bunch of code to call _get_json for last month *** 
			#"lm_Changed Type" = Table.TransformColumnTypes(lm_Table,{{"total", Int64.Type}})
		in
			#"lm_Changed Type",

    //*** Append data frrom last month and current month ***
    u_Source = Table.Combine({_lm, _cm})
in
    #"u_Source"

I have looked through many posts on this topic and have already followed the guidance as far as I can tell:

1. Ensured all the data sources are set to the same privacy level (back when the above was broken out into 5 separate functions and data sources: auth, get_json, current_month, last_month, union)
2. Dropped the privacy levels setting to Always ignore Privacy Level settings
3. Dropped the native database query setting to not require user approval for new native database queries
4. Dropped the data extensions to (Not Recommended) Allow any extension to load without validation or warning
5. Consolidated what started as 5 separate functions/datasets into the single one pseudocoded above

    

This issue happens consistently in that it always works in desktop and always fails when refreshing in the service. As far as I can tell, there hasn't been clear guidance on how to solve this problem definitively, at least based on everything I've read. 

Would appreciate any help from Power Query/Power BI experts here, and thanks in advance.