Here is my software:
ZCS 8.6.0 FOSS edition
Android 4.4.2 using DAVDroid to sync calendar via CalDAV
Some events that I create in the zimbra AJAX calendar show a slightly faded colouring in the appointment(not through being tagged with colours), and I've noted that these 'faded' appointments do not sync into my phone.
I noticed this on an event that I originally imported via an .ics from meetup.com, but then I manually created the same worded event, and I ended up with the faded look, but when I deleted the Location entry, it would get its colour back and sync to my phone.
Attached is a picture from my calendar to show the faded look, it happens in all colours, it's just more obvious in some colours than others.
There is nothing inside the event that indicates any difference between them, just the faded look in day/week/workweek/month view.
I have assumed that this issue is a ZCS issue and not a DAVDroid issue, because the event was created from the Zimbra AJAX interface and this faded colour issue is happening.
My phone won't let me import those .ics files directly into it so I can't try out the reverse as such, but I'm open to any suggestions.