Differences in valuation segment: & & & (Current / Calculated value)

What causes this issue?

The excise duty value for the excise duty-paid materials is calculated
by multiplying the current excise duty quantity for the material with
the current excise duty rate from table OIH01 (Excise Duty Rates
Table). This value is then compared with the current excise duty value
held in the valuation segment for the material. Any difference between
the two values is displayed in the report output.
If the report finds any differences between the excise duty value in
the valuation segment of a material and the calculated excise duty
value, the report status is set to 'ERR', and local currency conversion
is not allowed. If there are any differences, you should run report
ROIHEW20 to analyse the differences.

Error message extract from SAP system. Copyright SAP SE.