@stevedennis no worries.
We have most of our builds in sub-projects.
In this case, 'WebProjects' is a top-level project and 'Replicator' is a sub-project of that. In that sub-project, we could have any number of different build configs.
I moved the WebProjects_Replicator project to the root level and renamed it to just 'Replicator'. I then recreated the TC connection and attempted to import builds. I get the same result. The CI Build dropdown does not populate.
I even removed an other build config in that project so it ends up being 1 top-level project with 1 build config in it. No dice.

As for credentials, if they were wrong, the connection would probably show me Error instead of Synced

@atripp OK.
Using the url - /app/rest/builds?locator=defaultFilter:false,project:WebProjects_Replicator&fields=build(id,number,status,state,webUrl,startDate,buildTypeId)

I get this when calling the API:

and this when looking at the TC UI:

So, that lines up.
Not quite sure why I dont get a build list in BuildMaster.

@atripp Thanks for the reply. Let me try a few things and get back to you.

We're attempting to setup Buildmaster to have it serve as a deployment and test arm of our builds based on build artifacts.
The connection to TC seems to work. We do get the list of projects from the server.

BM also says that TC has been synchronized.

But when we go to import builds so we can see the artifacts, the dropdown never populates.

What API calls are you using that is supposed to return that info?
TeamCity version is TeamCity Professional 2025.11 Build 207946
and BuildMaster is version Version 2025.5 (Build 14).

We're kind of at a standstill until we can get the artifacts list.