I updated my iPhone 4 to iOS5 yesterday morning, and noticed after the install was complete that the contacts seem to have disappeared completely from my phone after setting the Preference for them to sync with iCloud.
Find a forum post from July suggesting creating a new text message in the Messages app and typing the first few characters of a contact's name to see if they still exist - which works, suggesting that having the contacts sync with iCloud causes some bug where the contacts merely aren't displayed in the Contacts app.
I then turned off iCloud-syncing for Contacts, and all my contacts were displayed normally again.
A few hours later, I test turning iCloud-sync for Contacts back on, notice no side effects; login to www.icloud.com later and see all of my contacts listed there.
Then this morning I open the Contacts app on the phone and it displays no contacts again. Turning iCloud syncing back off fixes it again.
Is there a better way to fix this and a way to fix it so that it doesn't happen in the future?