With quant inventory, new item or single entry not allowed

What causes this issue?

For <DS:DE.LVS_INVCC>Cycle Counting</> per quant, only the quants
entered in the inventory document can be counted. It is not possible to
add a further inventory item manually, or to enter inventory data per
individual entry.

System Response

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

How to fix this error?

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.