Hey Ajay,
I am facing a similar issue. There was no recent change in design of the BPM.
Some messages for the BPM were found stuck in error & we checked that the status of the nodes in Process adapter for BPM components in NWA was in error state with "Some components are missing" error.
Once the components were restarted they went into running status.
But some of the messages were not getting processed even after trying to resend.
Could you please share the steps in details that you had done to fix this issue.
Thanks in advance.