WCF service suddenly cannot find binding

I have a small WPF app with one WCF service.  

I use svcutil.exe to generate the client side code needed to support my services.    I have  been using this process for 10+ years for 100s of services and normally things work as expected.

Using VS 2019, I was working in the app today and suddenly the app hung a bit, some of the code pages looked like VS was confused about which code pages it was showing, then one of my web service methods had a parameter that I removed several hours ago.  (Everything has been working fine all day up to this point).

I removed the parameter again, cleaned and rebuilt the solution, ran svcutil.exe again, then tried to run the solution and instantly I get the dreaded error:

Could not find default endpoint element that references contract 'MainService' in the ServiceModel client configuration section.

Everything should be perfect but for the life of me I cannot determine why this doesn't work anymore.

This is from the App.config:

<system.serviceModel><bindings><customBinding><binding name="CustomBinding_MainService"><binaryMessageEncoding /><httpTransport maxReceivedMessageSize = "2147483647" maxBufferSize = "2147483647" /></binding ></customBinding></bindings><client><endpoint address="http://localhost:18418/WS/Ap/Main/MainService.svc"
                binding="customBinding" bindingConfiguration="CustomBinding_MainService"
                contract="MainService" name="CustomBinding_MainService" /></client><extensions /></system.serviceModel>

and this is from the web.config:

<bindings><customBinding><binding name="VelocityService.MainService.customBinding0" closeTimeout="00:11:00" openTimeout="00:11:00" receiveTimeout="00:11:00" sendTimeout="00:11:00"><binaryMessageEncoding maxReadPoolSize="2147483647" maxWritePoolSize="2147483647" maxSessionSize="2147483647"><readerQuotas maxDepth="2147483647" maxStringContentLength="2147483647" maxArrayLength="2147483647" maxBytesPerRead="2147483647" maxNameTableCharCount="2147483647" /></binaryMessageEncoding><httpTransport maxReceivedMessageSize="2147483646" /></binding></customBinding></bindings><serviceHostingEnvironment aspNetCompatibilityEnabled="true" multipleSiteBindingsEnabled="true" /><services><service name="VelocityService.MainService"><endpoint address="" binding="customBinding" bindingConfiguration="VelocityService.MainService.customBinding0" contract="VelocityService.MainService" /><endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange" /></service></services>

Any ideas on how to trouble shoot this?

Thank you.