Don’t think I have tried time-coloring via events so it is possibly/probably it is a bug. Perhaps you can try to add a suitable -f option to events, i.e. -f?T where ? is the column number with your date used for CPT lookup. I think -f2T for you. You can also do some sleuting by using the events -Q option and examine the intermediate data file going into plot via events. Just do this for one frame via movie -M and use -Fnone.