PBCS Financial Reporting Drill through using related content issues POST function instead of GET

We have SSO enabled using AAD authentication in PBCS.

We want to drill through to a Power BI report ensuring we are authenticated through the whole process ..

We are using Azure Function App and utilising a http trigger function that reads the URL and remaps the $CONTEXT$ pov information into a format required by power bi and redirects to the appropriated Power BI Report .

The Function App has been configured to use AAD (Azure AD). If we copy and paste the expanded url it authenticates fine a processing continues as expected

However when run from Financial Reporting we get an error saying we do not have access to the directory .  Investigation reveals that FR is performing a POST function on the URL and the Azure function app does not accept this. When the function is GET it authenticates correctly an proceeds to the next stage.