In FE, the missing slur is most probably an oversight related to the introduction of bass clef to the notation of f. Anyway, it must be an inaccuracy, which was corrected already in GE and EE.
Distraction of the engraver of FE is proved also by the missing initial fragment of the next slur – it is only its ending in bar 208, on a new line, that was printed.
Compare the passage in the sources »
category imprint: Differences between sources
issues: EE revisions, Inaccuracies in FE, GE revisions, Uncertain slur continuation
notation: Slurs