APEX Page URL Parameter vanishes when called from Oracle Fusion

Summary:

When called APEX page URL along with parameters is called from third party, the URL parameters are not sent to the calling page.

Content (please ensure you mask any confidential information):

We have built a APEX application where one of the page looks for URL parameter (P_REQ_ID). From Fusion, Procurement requisition page, we have called the page URL with the parameter as P_REQ_ID like below:

https://servername/ords/r/client_workspace/comm1005/comm?P_REQ_ID=300000020790131

On page load, when I try to access P_REQ_ID parameter, it is not there.

We are using SSO for this.