Fixed & is missing for materials with product type 3 ("Chemicals")

What causes this issue?

"Chemical" products (Product type 3 in the conversion group, which
corresponds to API/ASTM tables 6C, 24C, 54C, 60C)) require a fixed
density/gravity and thermal expansion coefficient before quantities for
such products can be calculated from mass to volume or from volume to
mass.
This data has to be maintained correctly for chemical products in the
material master.

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

The API c-code routines of type C (6C, 24C, 54C, 60C) should be used:
(from: THE USE OF THE PETROLEUM MEASUREMENT TABLES - Manual of
Petroleum Measurement Standards, Chapter 11.1 (API Std. 2540, ASTM
D1250, IP200, ISO 91-1, Revised October 1995))
if tables of type A or B do not appear to adequately represent the
thermal expansion properties of interest.
if precise thermal expansion coefficients may be obtained directly or
indirectly by experiment
if buyer and seller agree that, for their use, a greater degree of
equity can be obtained

System Response

How to fix this error?

Enter the correct gravity, relative density and density for this
material.

Error message extract from SAP system. Copyright SAP SE.