When you say side-by-side is that two copies of xLights running? We do want to prevent all possibilities of a crash so I'd like to get to the bottom of how you did it. There are other ways you can try though. Turn off the timing tracks and drag select with the yellow dashed box. Or create a fixed timing track of 50ms so you have a whole lot of cells to select from. Maybe having all the effects inside one cell is a problem.
