Perforce agent side checkout not using latest change

I have a build configuration that uses a shared client. I've created a VCS root with custom sync arguments `sync -n` to allow TeamCity to monitor changes while preventing it from actually syncing any files from the VCS root itself.

I've followed all of the steps outlined for a shared client - 

• Set `teamcity.agent.failBuildOnCleanCheckout=ignoreAndContinue`
• Set `teamcity.perforce.agent.reuse.client=true`
• Set `teamcity.internal.bootstrap.steps.enabled=true` to enable bootstrap sets
• Added bootstrap steps that sync the shared client to `vcsroot.build.number`
• Set a checkout rule of `-:.` to prevent creation of a client for the VCS root

The build number that TeamCity is using if I click Run is static - it does not use the latest revision.  If I click the ellipsis next to run I can manually specify the latest change. I've verified in the `vcs` server log that TeamCity is correctly polling my VCS root for changes.

What do I need to modify in order to use the LATEST change when running the build configuration?