In AT the slur beginning in bar 18 reaches simply until the end of the manuscript, which perhaps influenced the simplified notation without marking the return of the initial thought of the Etude.
In AW the slur reaches – inaccurately – until the end of bar 17, while bars 18-19 are generally not embraced with a slur. However, it seems that the slur being a brace limiting the range of the first volta was treated by Chopin as phrasing one (similarly the slur of the second volta in bar 20).
Compare the passage in the sources »
category imprint: Interpretations within context; Differences between sources; Corrections & alterations
notation: Slurs