Angular universal 7 not making http calls
Thanks to @CaerusKaru for solving this one in the @nguniversal issues page! https://github.com/angular/universal/issues/1046#issuecomment-455408250
Essentially, the problem was the interceptor I use to append the full server path to api calls. It was using Object.assign(request, {url: fullServerUrl}); to set the new url for all http requests beginning with /. The appropriate method is apparently request.clone({url: fullServerUrl}); and changing that one snippet caused the data to flow like a rushing stream.
Hope this helps someone else, and I will be turning the repro-repo (hard to say and type) in to boilerplate of Angular7 and Universal as a working starter point.