Ok.
I'm not sure if this will just be temporary or long term, but I removed the "agenda" app 4x4 from the home slide page and reinserted the app in the same window, and it is working correctly with all calenders.
Hope it sticks.
FYI: I picked up my LTE on the 18th and as of the 5th of June, my calender sync has stopped also. All settings are checked to sync.
For the record, though. I am rooted W/ Wifi Tether. Is it possible they are connected?
Thanks