Split valuation is not allowed for value-only materials

What causes this issue?

You have specified a <DS:GLOS.valuation_category>valuation category</>
for this material. However, since the material is a
<DS:GLOS.value-only_material>value-only material</> (such that the
material type allows the updating of values, but not quantities), the
system does not allow you to enter a valuation category because it is
not possible to manage materials of this kind in separate stocks.

System Response

The system resets your entry.

How to fix this error?

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

Error message extract from SAP system. Copyright SAP SE.