Hang in there man, I know that feeling! Too often do we face issues like this, we're underappreciated.

Did you turn on verbose logging and look at all of the errors? This solved it for me, for me it was due to User Script Sandboxing as mentioned above. Thus, I think the warnings are just that, warnings, but there is most likely another underlying issue for your build.

I agree that it's the code signing issue for you, I compared your logs to mine and that's the only issue I can see. AFAIK you need to ensure you're signing with a valid certificate, however, I believe you can turn signing off for debug builds (I believe it might be necessary to turn it off). Others have commented that deleting the certificate and making a new one fixed a similar issue.

Sure, but I think the important thing is to note that it's just a warning, there are other reasons why the builds are failing, as in my case. If you look at the verbose version of the logs it's likely you can fix the build failure, while the warning persists until fixed by Apple.