Cache malformed in default email
If you don't have de default mail visible with all roles, the cache could be malformed. If after clear cache a user without permissions generate the cache the default email will be emtpy.
The key of the cache CRM_OG_fromemailaddress_xxxxx
Cache is generate with this request
CRM_Core_OptionGroup::values('from_email_address', NULL, NULL, NULL, ' AND is_default = 1');