I do found a bug in GUI 186 calendar part :
whatever you to be in daily or month view,
when you select a date with an event, if you edit that event
and change the applied color, any color update you may
try is NOT taken into account.
As workaround, create a dummy new event,
and restart editing previous one.
Color change is now taken into account.
As from now, any edit got changes applied.
Happy fixing
Th