I had this same issue on my end. Your post helped me figure out what the issue was. here is my service model section. I discovered that the keys were the httpsGetEnabled then setting the bindingconfiguration I hope this helps.
<system.serviceModel>
<behaviors>
<serviceBehaviors>
<behavior name="RequestImageBehavior">
<serviceMetadata **httpsGetEnabled**="true" />
<serviceDebug includeExceptionDetailInFaults="false" />
<dataContractSerializer maxItemsInObjectGraph="1073741824" />
</behavior>
</serviceBehaviors>
</behaviors>
<services>
<service behaviorConfiguration="RequestImageBehavior" name="RequestImage">
<endpoint address=""
binding="wsHttpBinding"
**bindingConfiguration**="HttpsBinding"
contract="IRequestImage">
</endpoint>
<endpoint address="mex"
binding="mexHttpBinding"
contract="IMetadataExchange" />
</service>
</services>
<bindings>
**<wsHttpBinding>
<binding name="HttpsBinding">
<security mode="Transport">
<transport clientCredentialType="None"/>
</security>
</binding>
</wsHttpBinding>**
</bindings>
</system.serviceModel>