Upper bounds check at "ontouchend" will stop swiping at second or third picture (depends on screen type) using classic theme.
Calculation of
isPastBounds = !this.index && this.deltaX > 0 ||
this.index == this.length - 1 && this.deltaX < 0;
uses "this.length" value which is not the count of pictures in galleria (in most cases the value is "2" or "3"). This will stop increment of index and result in showing the same picture again. This only happens using swipe gesture. (galleria.js, line 6859)
Using
isPastBounds = !this.index && this.deltaX > 0 || this.index == this.child.childElementCount - 1 - 1 && this.deltaX < 0;
instead would solve the issue.