We are having an issue with a service request invoicing.
The issue occurs when we issue the material line, then unissue the material line as the component was not needed nor used.
On material issue a sales line is created.
On material unissue the sales line is not removed, a negative sales line is added.
The issue is at time of invoicing, the system is attempting to invoice a $0 amount and stopping the process from moving forward.
Wondering if we are missing something obvious, or if this is a bug?
Screenshots below





