My calendar appointments spontaneously lost all of their colour categories. I still have all of the custom categories in the list for selection, but all of the actual appointments lost their colours. I started reinstating them and the same thing happened again, and this time I have lost a recurring appointment as well. This is not such a problem for the future, but I need to keep track of previous occurrences which are now gone. All of the posts I have seen regarding this describe the categories in the selector changing from their custom names to things like "blue category" or "orange category" but that has not happened in this case, so the recommendation to re-name the colour category thereby reinstating the colours on the calendar does not work here.