TeamCity NuGet Restore returns code 0 but packages are not actually restored

I'm having an issue with one build configuration and not another.

The first configuration works as expected and I can see that it is installing nuget packages when restoring.

The second configuration says the nuget restore returned a code of 0 and moves on to the VS build step, but that step fails because there weren't actually any packages installed.

Successful build log shows the GET and OK from the NuGet feeds and reports that the packages were actually installed, but the failing build doesn't have that information.

and the failing build log looks like this:

This is a serious issue for us right now and I can't find anything that would break this.

Here are some screenshots of the step configurations successful first:

(and the failing configuration, which is not a template and explicitly identifies the sources because there's 1 extra to use than is found in the nuget.config on the agent)