Shipping point &1 is assigned to more than one plant

What causes this issue?

For shipping points with no address number, the system assigns the
address number of the assigned plant. The precondition for this is that
the shipping point is assigned to only one plant.
This shipping point is already assigned to more than one plant. This
means that there are multiple addresses to select from. The system
cannot assign an address. Edit the shipping point data to specify an
address. For more information see Customizing under <LS>Enterprise
Structure</> -> <LS>Definition</> -> <LS>Logistics Execution</> ->
<LS>Define, copy, delete, check shipping point</>.

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.