Well, first of all you can check that the changeset was included in the build that produced the deployable package that you deployed to test. You can see this in the Build pipelines page, where you see your build history (assuming you are using a build VM).
Then you can check from your Tier2 environment history that the package was surely deployed.
Finally, it's possible that the code is there but doesn't work expectedly in your Tier2 for some reason (for example different data). If this is the case, maybe you could share your code and we can check if it raises any suspicion.