Miss Fortune Strut-Mark/Dash Oversight/Bug

Upon playing a recent ARAM game as Miss Fortune, I noticed quite a few times that being hit by the Snowball of Mark/Dash, despite it doing damage and applying a debuff to Miss Fortune, it does not break nor reset the Strut passive, and her movement speed will remain completely intact from the passive.

Unless I've misunderstood, even the minute damage Mark does should break the passive, since it is non-periodic. Only a minor discrepancy, but yeah. I guess that's a thing.