Have EL Capitan beta and I'm noticing that my ICLOUD account is completely unchecked and will not allow me to check boxes hence my imac and iphone are NOT in synch with my ICLOUD calendar.
ICLOUD ISSUES
Hi Remmy,
I had a similar issue back with Beta 1. I solved it by deleting all files from the following folder (from Finder press shift+cmd+G and copy paste the following in):
~/Library/Application Support/iCloud/Accounts
After a restart, I was then able to get into the iCloud preference pane, where it asked me for my new password. After giving it, all was working again.
Max.
Is it working for you?