I want to bump this topic since we are experienceing the same issue:
We place our order and when we come back to the SRM the cart is empty.
It works with the default Portal desktop but not with our customized ajax framework although we use the same sources as the default ajax desktop (in which it works also).
it seems like we can confirm Anubhav Jain's observation, that, why ever, the session (SID) is lost when we come back.
Has there been found any solution yet, and is someone eager to share it with us?
Kind regards
Ingo Schindler