Nothing was allocated in the sender-receiver relationship(s)

What causes this issue?

The SAP System has detected a loop in the receiver-sender relationships
of the iteration which, although having one or more receivers outside
of the loop, nevertheless cannot allocate to them (at least in this
period).

System Response

Since this loop has no receivers ouside of it to which it can allocate
further, the iteration terminates.

How to fix this error?

Ensure that a receiver outside of the loop can be allocated to.

Error message extract from SAP system. Copyright SAP SE.