In A the 
restoring B
in the chord in the middle of the bar is missing. In A these accidentals are also absent the next two times this phrase appears, that is in bar 188 and 371. Nevertheless, the harmonic context indicates that it is a patent mistake by Chopin, which he committed earlier, perhaps when writing this movement as a draft, in which the subsequent appearances of this bar could have been marked in shorthand as repetitions of the first appearance. The flat was added in GE (→FE,EE,IE).
Compare the passage in the sources»
category imprint: Interpretations within context; Differences between sources
issues: Omissions to cancel alteration, GE revisions, Errors of A
notation: Pitch