Symptom
You receive the error "Enter only one true account assignment" when trying to post journal entry, since you have WBS element and Market Segment in Profitability Analysis acting as true account assignments.
Environment
SAP S/4HANA Cloud
Resolution
Profitability Segment always serves as true CO account assignment, although, it's possible to have a statistical WBS element.
If a true CO account assignment to WBS element is not required, you could alternatively make profitability segment the true CO account assignment and add WBS element on the account assignment screen of the profitability segment as attribute.
The other option would be to have WBS element as true account assignment and then use Profitability Analysis Substitution / Validation to derive the additional PA characteristics.
See Also
Keywords
Profitability Analysis, Market Segment, True Account Assignment, PA Characteristics, Substitution, Validation, WBS Element, Account Assignment , KBA , CO-PA-MD , Master Data , How To