INTERFACE_REGISTRATION_ERROR -sender/receiver pipeline

I have a scenario where I am getting Interface_registration_error. Please see attached screen shot. I have a synchronous interface called from external system via SAP-PI to SAP backend. This raises a quote and while synchronous interface is still active SAP-backend calls another asynchronous interface which sends email to external world. Please refer figure 1.

When right hand side interface is called separately (figure 2) it works fine but when asynchronous interface is called while synchronous interface is still active then it doesn't work.

Please see figure 4 which is sxmb_moni. The failed message is when interface is called while synchronous interface is still active and the success message is the one when its called separately (figure 2 interface). As you can see when its called as part of synchronous interface for some reason pipeline is showing Receiver. To me its looks like its not able to distinguish because synchronous interface is still active.

Please see the error message figure 3 (No implementing class registered for the interface (ABAP interface, request message , request message, namespace ).

This kind of integration used to work but after applying latest support packs it has stopped working. We are going to raise it with SAP but I thought I will check it here first if anyone else has experienced such problem and founf the solution. thanks