Formula.Firewall error using R Script

Hi,

I am calling a simple R script (for regular expressions) to combine with my source query. Latter is based on ODBC connector to AWS Simba Athena user DSN. All the datasources privacy level is set to same as "Organizational". I get the formula.firewall error. 

Formula.Firewall: Query 'Rtestfx' (step 'Run R script') references other queries or steps, so it may not directly access a data source. Please rebuild this data combination.

I have tried the technique prescribed in some of the online blogs to separate out the sources - stage the source query and wrap it inside a Function and then use that function output query to combine with R script. This also ended up with same error.

I don't want to "ignore the privacy levels" as I don't know if/what/how my source AWS data might be transferred to open source R environment and potentially putting it at risk. We also eventually need to publish this report in Power BI service hence the solution should work in both the desktop and the service.

Can anyone suggest any workable solution for this?

Below is my query dependency diagram for reference.

Thanks

Nirmit