Suppose two frames in a v5 trial each contain a non-complex action and are merged to each other. The data for each action is retained, but the player would ignore the second frame. In v6 conversion, the data for both is converted, and both actions are run. This can create glitches, such as when the second frame contains a case-breaking "hide a scene," as the third part of The Bitter Turnabout does.
See this related issue. It is currently unclear if the policy regarding the related glitch should be retained here, or if we should suppress those actions on merged frames, which v5 ignores.