osgi values not being saved in AEM 6.2

ConfigManager is not saving the values. It is taking default values always, any changes in osgi values are not being reflected after saving.

Sometimes it does save for few properties, Values are being saved when there is no warning icon

If there is warning icon, none of the values are saved. Moving cursor over the icon shows the following message

Note, that this property is not set. The above field contains is the *default value* specified in the Meta Type service.

My class has the following defination

@Component(label = "Apache Jackrabbit Oak Custom Sync Handler", name = "com.mycom.ldap.core.LdapSynchronizationHelper",
configurationFactory = true, metatype = true, ds = false)

public class LdapSynchronizerSettings {

Property is defined as

    @Property(label = "User Expiration Time", description = "Duration until a synced user gets expired (eg. '1h 30m' or '1d').", value = CONST_USER_EXPIRATION_TIME_DEFAULT)

Other class where the logic for synchronication helper (com.mycom.ldap.core.LdapSynchronizationHelper) is defined as

@Component(
        // note that the metatype information is generated from LdapSynchronizerSettings
        policy = ConfigurationPolicy.REQUIRE, immediate = true)
@Service
public class LdapSynchronizationHelper implements SyncHandler {