I've just updated a Joomla 2.5.28 site from an older version of CiviCRM (4.4) to the latest 4.7.29. Now I can't edit any of the fields under the "Contact Details" pane for existing records.
There are two errors:
When editing these fields for contacts that have custom subtypes, a popup appears saying "One or more contact subtypes have been de-selected from the list for this contact. Any custom data associated with de-selected subtype will be removed as long as the contact does not have a contact subtype still selected. Click OK to proceed, or Cancel to review your changes before saving."
For all contacts (including custom subtypes from item 1 above), saving doesn't work and throws this error: "Custom Addressee is a required field if Addressee is of type Customized."
It's also interesting that I can create NEW records of contact subtypes, but get the errors again if I try to update the Contact Details of the new record.
I found this post (Why after importing contact records were Addressee field values set to "Customized" for records where Custom Addressee had a null value?) which seems to address issue #1, but I'm a bit stumped as to issue #2. And I didn't want to try the correction suggested in this post until I knew if the two issues could be related.
Site details: Joomla 2.5.28 CiviCRM 4.7.29