Hi bradluettke
Which vCenter version & build are you running?
As explained in this blog post - vCenter Single Sign-On 5.5 - Backwards Compatible? | VMware vSphere Blog - VMware Blogs
The use case/drivers for LDAP bind is for interoperability with vSphere 5.1 when we are running a mixed version of vCenter 5.1 and its Inventory Service against vCenter 5.5 SSO and Web Client 5.5
Do you have two-way trust setup as per this KB? VMware KB: Microsoft Active Directory Trusts supported with VMware vCenter Single Sign-On
Other KB for your references:
VMware KB: Supported vCenter Single Sign-On 5.5 configuration and interoperability with vSphere 5.1
VMware KB: Creating and using a Service Principal Account in vCenter Single Sign-On 5.5
Thanks,
Bayu