I have been having the same problem. I went into the Genius bar and they claim it works fine. They removed iCloud. They also removed the Yahoo contact and reloaded it. It worked while I was there, then it failed.
I have a contact list of 800+ contacts. In this list I tried to update existing yahoo contacts. I can add iDevice contacts and they will show in yahoo, but not vice versa (unless i unload/reload). Edits to either iDevice or Yahoo do not get registered.
I contacted Yahoo and received a canned response on how to load contacts. Same as seen on this thread.
Next I created a new Yahoo account. It had no contacts. I added the account to iDevice (iOS5) and this seems to work as expected. additions to Yahoo or iDevice are sync, it does take some refresh on iDevice of all contacts (takes 2-3 minutes on my iPhone4s). I press the refresh contacts button a few times (curved arrow button upper left corner of the Contact Groups page). Edits on either iDevice and iPhone are sync as well.
There is something flaky about Yahoo contacts and iDevice. I can't put my finger on it. There might be a time out issue with sync of many contacts. It seems to work on some contacts but not others.
It is a problem because you can't tell which contacts on the iDevice yahoo contact list actually go updated in yahoo and which have not.
BTW as said earlier here. You do not need CardDAV account in iOS5, just the yahoo account and turn on Contacts
Below response from Yahoo support (it does take 2-3 days to respond - but they do respond with a canned response)
From: Yahoo! Address Book <address-book-feedback@cc.yahoo-inc.com>;
Thank you for writing to Yahoo! Address Book.
I see from your email that Facebook contacts which have additional
information (beyond just an email address) do not sync from your Yahoo!
Contacts to your iPhone. I also gather that edits you make on your
iPhone do not take in your Yahoo! Contacts. I can certainly understand
your concern, and would like to be of assistance.
If you recently upgraded the operating system on your iPhone such as
with the recent release of iOS 5 software for the Apple iDevice, that
could be the cause of the missing contacts.
You can delete the Yahoo! account from your Apple iDevice and recreate
it, forcing a new sync.
To remove your Yahoo! CardDAV account from your iDevice:
1. Go to your iPhone, iPad, or iPod Touch settings application
2. Tap "Mail, Contacts, Calendars"
3. Tap "Yahoo! - Contacts"
4. Tap "Delete Account", Confirm deletion by tapping "Delete Account"
once again.
How to sync your Yahoo! Calendar and Yahoo! Address Book with your
iDevice (iPhone, iPod Touch, iPad)
1. Go to your iDevice's "Settings" application
2. Tap "Mail, Contacts, Calendars"
3. Tap "Add Account" & then tap "Yahoo!". You may already have a "Yahoo!
Mail, Contacts, Reminders, and Notes" account set up, if so just tap it
under the accounts section.
4. Enter your Name, Yahoo! E-Mail address & Password. You do not need to
change anything in the "Description" field unless you wish to. Tap the
"Next" button, upper right hand corner, when you have entered the
information and Yahoo! will verify your account information.
5. Click the "Save" button in the upper right hand corner
6. You can come back to "Yahoo! Mail, Contacts, Reminders, Notes" to
disable syncing for all or specific Yahoo! Services or to delete your
Yahoo! Account from your Apple iDevice.
7. To ensure proper syncing between your iDevice's Contacts and Yahoo!
Address Book, please make sure the "Default Account" account is set to
"Yahoo!" for "Contacts" found towards the bottom of the settings for
"Mail, Contacts, and Calendars".
Please note that CardDAV accounts are no longer needed on your iDevice
to sync with Yahoo!"s services and you may delete them if you have them
set up on your iDevice. If you have them and do not delete them from
your iDevice, you risk getting duplicate contacts on your iDevice and in
Yahoo! Address Book or Yahoo! Contacts.
I hope I have understood and answered your inquiry, if not, or if you
have any other questions or concerns, please respond to this email and
we will gladly assist you further.
Thank you again for contacting Yahoo! Address Book.
Kind regards,
Tyler
Yahoo! Address Book Customer Care
Address Book Backlog Tech T3 Replies
For assistance with all Yahoo! services, please visit:
http://help.yahoo.com/
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