What causes this issue?

According to the documentation, the due date for flows is needed in
order to determine these fields:
Remaining term
Days overdue

System Response

Since the system does not yet recognize due dates for parallel valuation
areas in position management, the system uses the position value date
instead of due dates to calculate the above fields.

How to fix this error?

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

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.