Here are my two cent on this. The change event policy does not help in all cases. Your seams one of those cases it does not, at least not in your version. In his blog Andrejus talked about a special use case, which together with bad practice made ppr as change event policy not work. There sure is a reason for the ppr, and that is what Steve pointed out.
I can't give an answer to why ppr it's not work in your case, but it think the reason is that you don't fragments but pages. Try ui implement the use case using fragments and see if the ppr works out then.
Hi Timo, page B has to be a page. So, to use page A as a fragment, I moved page B to another bounded tf. Using the same bean in pageFlowScope for both taskflows. However, now when I hit save on pageB which commits and then executes adfFacesContext.returnFromDialog, I get the error: Caused by: oracle.adf.controller.ControllerException: ADFC-12001: The ADF Controller is attempting to pop last entry from page flow scope stack.
The solution mentioned here is to invoke the dialog:<control_flow> target page directly instead of having pageB in its own taskflow: The Incident Archive: ADF ADFC-12001 ControllerException pop last entry from page flow scope stack
But if that's the case then we can only try with pages and not fragments