Why fields in 'Edit Tax determinants' are null for 'Invoice only line'

Summary:

Why fields in 'Edit Tax determinants' are null for 'Invoice only line'

Content (please ensure you mask any confidential information):

We create SO with 2 items in lines and 3rd line is Invoice only line.

The values that populate in 'Edit Tax determinants' are null for 'Invoice only line' but for rest two lines we can see the expected values

Version (include the version you are using, if applicable):

25B

Code Snippet (add any code snippets that support your topic, if applicable):

For Line 1 (Line type : Buy)

For line for which it is null (Invoice only line):

As 'Tax Classification code " is blank , it is impacting tax computation. Please suggest why the fields are null.