Construction type is automatically set to &1

What causes this issue?

Synchronous maintenance of material number and construction type are
intended for this type of equipment in Customizing for PM and CS. This
means that if the material number is maintained, then the construction
type must have the same value.

System Response

The construction type of the equipment was not previously maintained.
The system automatically sets the value to the material number, that
is, &V1&.

How to fix this error?

Changes are only possible to synchronously maintained values using the
material number. If you do not want synchronous data storage, then you
should either change the type of the equipment or change the settings
in Customizing.

Error message extract from SAP system. Copyright SAP SE.