The largest conflict created by Mary Shelley's narrative technique, in Frankenstein, is one the reader faces. Frankenstein is a frame story. (A frame story/narrative is a story within another story.) For this novel, the main storyteller is Robert Walton, an explorer in search of the seat of magnetism and a faster route for seafarers.
The conflict arises when the story takes a turn; the perspective is changed from that of Walton to Victor's. This said, it does not really change to Victor's perspective. Instead, Victor's story is told by Walton. As the story continues and deepens, the perspective changes again (on the surface). As "Victor" recalls the creature's story, the creature's voice takes over. Later, the story becomes Victor's again; finally moving back to Walton. While this seems to be the superficial movement of the narrative voice, many readers forget that the entire story is actually narrated by Walton.
I have resolved every night, when I am not imperatively occupied by my duties, to record, as nearly as possible in his own words, what he has related during the day. If I should be engaged, I will at least make notes.
Based upon this, one could state that the greatest conflict which exists in the novel is the forgetfulness of the reader that it is Walton's voice telling the tale of Victor Frankenstein and his "son."