The problem was that DXA is using an older version of the CIL out the box. Updating the references to the later versions available on nuget.org resolves the problem.
The following steps fixed this issue.
Upgrade the Sdl.Web.Delivery version to 11.1.1103 from NuGet.
Updated the DXA Webapp web.config to resolve all the conflicts
When you are trying to create a page with regions, Tridion would give a notification asking you to update the set of nested Regions to make it valid. In the Event System code, you would want to perform this update by calling the SynchronizeWithSchema method on the page.
You would also have to set the page metadata schema with the correct root element ...