Not possible to delete line items in the case of price summary &1

What causes this issue?

The variant that was active when the termination occurred tried to
delete billing line items or set them to inactive. However, the items
to delete include items that have been defined as belonging to a price
summary.
Price summaries can only be deleted or set to inactive completely. In
this case, at least one of the billing line items that is part of the
price summary could not be deleted. It is likely that a contrary output
operand (operand type AMOUNT) has been used in one of the corresponding
schema steps.
Partial deletion is not possible, as it could result in rounding
differences that could no longer be corrected. The corresponding
configuration in the schema is highly irregular. Still, if you
absolutely require this configuration, please report the termination to
SAP.

System Response

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

How to fix this error?

Check the corresponding schema. All the steps involving price summary
must have the same output operand for operand type AMOUNT in order to
enable deletion (or setting to inactive) in a subsequent step.

Error message extract from SAP system. Copyright SAP SE.