You have activated the creation of automatic reservations via the APP "Settings for Creation of Reservation" as described in the attached BLOG. As described in the pre-requisites the creation of the reservation is dependent on stock availabilty. Yet, despite your material having no available stock the system is still generating a reservation when you create a Purchase Requisition via the SSP APP 'Create Purchase Requisitions'.
SAP S/4HANA Cloud All versions
Reproducing the Issue
1) Set an entry for a material group and purchasing group combination in the APP 'Settings for Creation of Reservation'.
2) Open the APP 'Create Purchase Requisitions'.
3) Create a Purchase Requisition with a real account assignment for the given material, material group and purchasing group.
4) Save the Purchase Requisition.
5) Open the APP 'My Purchase Requisitions' and search for your new Purchase Requisition.
6) Confirm the status is ‘Follow on Document Created’ and the automatic reservation is visible.
Standard System Behaviour, the material is defined for 'No availibilty check' in the Material Master.
The real availibilty check is executed only for Materials that are relevant for availabilty check.
This can be seen in the APP 'Display Material' (MM03) in the MRP3 TAB
The APP Monitor Product Availability (CO09) shows the true availability of a material.
In APP 'Monitor Product Availability (CO09)', when a material is set with 'no availability check' you will receive the following message:
No display: Material not relevant to check, therefore always available (Message no. AG772)
Process description BLOG
CL_MMPUR_SSP_RESERVATION, CHECK_STOCK_AVAILABLE, EV_RESRV_ALLOWED, LV_CHECK_RULE, LS_WMDVEX-COM_QTY, ESTKZ, MARC-MTVFP, EBAN-RSNUM , KBA , MM-FIO-PUR-REQ-SSP , Fiori UI for Self Service Procurement , MM-IM-RS , Reservations , How To