Unable to turn on LDAP or Multiple AD authentication

Every time I attempt to login with Multiple AD auth, I get this error and am unable to actually get AD auth to work: An error occurred in the web application: Exception of type 'System.Web.HttpUnhandledException' was thrown.

Details:

URL: http://mriczelkeapt001/administration/security/change-directory?directoryId=3
Referrer: http://mriczelkeapt001/administration/security/change-directory?directoryId=3
User: Admin
User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; Trident/7.0; rv:11.0) like Gecko
Stack trace: at System.Web.UI.Page.HandleError(Exception e)
at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
at System.Web.UI.Page.ProcessRequest(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
at System.Web.UI.Page.ProcessRequest()
at System.Web.UI.Page.ProcessRequest(HttpContext context)
at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)

If I try LDAP, I get this error: An error occurred in the web application: The time limit for this request was exceeded.

Details:

URL: http://mriczelkeapt001/0x44/ProGet.WebApplication/Inedo.ProGet.WebApplication.Controls.PrincipalPicker/FindPrincipals?directoryId=2&filter=a&principalTypes=3&_=1441724871006
Referrer: http://mriczelkeapt001/administration/security/privileges/add?directoryId=2
User: Admin
User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; Trident/7.0; rv:11.0) like Gecko
Stack trace: at System.DirectoryServices.SearchResultCollection.ResultsEnumerator.MoveNext()
at Inedo.ProGet.WebApplication.Security.UserDirectory.LdapDirectory.FindUsers(String searchTerm)
at Inedo.ProGet.WebApplication.Security.UserDirectory.LdapDirectoryBase.FindPrincipals(String searchTerm)
at Inedo.ProGet.WebApplication.Controls.PrincipalPicker.FindPrincipals(Int32 directoryId, String filter, Int32 principalTypes)

Product: ProGet
Version: 3.8.0

Most likely, the service account being used by ProGet WebApp does not have privileges to query the domain, or the domain is unreachable due to some proxy configuration.

The account was able to successfully query for my LDAP login and let me add my users in the UI on the privileges page. If it is able to do that, doesn't that mean the configured user has access to query the domain?

This answer doesn't answer the question. Is there anything else to check or try?