Build setup fails silently

I have a Pipeline with a couple of caches (node, bower) and a Docker service container. Sometimes the "Build setup" step fails to complete silently:

• umask 000
• git clone --branch="master" --depth 50 ...
  Cloning into '/opt/atlassian/pipelines/agent/build'...
  HEAD is now at ...
• chmod 777 $BUILD_DIR
  Cache "node": Downloading
  Cache "node": Extracting
  <no more output>

If I rerun it, it usually works.

• umask 000
• git clone --branch="master" --depth 50 ...
  Cloning into '/opt/atlassian/pipelines/agent/build'...
  HEAD is now at ...
• chmod 777 $BUILD_DIR
  Cache "node": Downloading
  Cache "node": Extracting
  Cache "node": Extracted
  Cache "bower": Downloading
  Cache "bower": Extracting
  Cache "bower": Extracted

I suspect that there is some internal ~2 minute timeout on the "Build setup" step...when it works, it usually takes about 1.5 minutes (which is really slow compared to the 1.5 seconds it takes on my laptop if everything is already cached, but these are known issues). I suppose there are a few separate issues:

1. How do I debug "Build setup" failures?
2. Is there a timeout for this step? Can it be increased?
3. Are there any logs for the service container? If the service container fails to deploy, how would I know?