What causes this issue?

The system could not find the transportation connection point in the
database. For this reason, it did not propose default values for the
waiting time in a route stage of stage type 'border' or 'load
transfer'.

System Response

The route stage does not have default values.

How to fix this error?

If you want to have default values, you should first save all
transportation connection points that you entered in the database. The
system will then find existing default values.

Error message extract from SAP system. Copyright SAP SE.