iMovie MP4s imported inti Moho animation app automatically create cycling. Can this be stopped?

Moho is an animation app. MP4s can be imported to make a layer of animation. MP4s made by Moho can be imported to Moho and they won't automatically create a cycle (the layer is visible on and off during the animation). When a MP4 made in iMovie is imported, a cycle is automatically created. Moho support says the problem is not with their app, as other MP4s do not cause this problem. They suggest changing the settings in iMovie, but I can't see which ones would do this.