Custom build changes using the most recent commit from default branch, not from specified build tag

I have a build configuration that runs tests from a specific VCS root. The default branch is master and the git repository that the VCS root points to uses release tags for weekly releases.

Since I have several other build configurations just like this one with tests against different repositories, I have a separate build configuration (within the same project) that is environment specific and triggers each of the test build chains.

Ex: 
"Test Project" has:

- VCS root "API-Tests-A" in one config
- VCS root "API-Tests-B" in another config 
- Environment Config with no vcs root that triggers builds of API-Tests A & B

I want the ability to run this environment config and specify the release tag that it should build in each of the API-Test configs. Since I am using the environment config, I used reverse dependency params on the custom build of the environment config to specify the *teamcity.build.branch* for each of the test configs. This seemingly works based on the label in the UI. 

However,  this is not actually triggering a change in the build.vcs.number to the most recent commit for the tag... it is using the most recent commit on the default branch. So it shows me in the UI that tag 17.09.27 is being built, but in the build log it shows the computed revision as the most recent commit off of master. 

On an individual custom build dialog, I noticed that the "Include Changes" dropdown does not filter the most recent commits to the most recent commits for that tag either, I have to specifically update this field in addition to the build branch to a commit that I know was the last one for the tag.

If there is no way to have the build branch indicate that the 'latest changes to include' should use the most recent commit from the teamcity.build.branch (the solution I would prefer) - Is there a teamcity predefined parameter than I can use to update this field using a reverse dependency in the same way that I am updating the build branch?

Other possibly useful information:

1. There are checkout rules on each VCS root. 
2. There are no build triggers set up. 
3. Versioned settings are disabled. 
4. I do have "Enable to use tags in the branch specification" checked on my VCS root. 
5. My branch specification is setup with: 
+:refs/heads/*
+:refs/tags/*