I had the same issue but solved it by computing my own “best channel” PowerShell scriptlet that I execute from the TC build using the exposed OctopusDeploy REST API.
I’m home now, but will post my solution for you tomorrow when I get into work!
Thanks for getting in touch! The Team City version does not match the Octo.exe version, they aren’t kept in sync. But the latest release has the octo.exe version packaged within it.
For posterity then… here’s how I solved this same issue by matching git branch name with the best match od channel (or default if none found) in a TeamCity Powershell Runner: