Hi Kiran,
This looks to be a compatibility issue with the older Tree Table widget used in the TcConnector sample.
The latest Teamcenter Connector Toolbox Samples release has already removed the dependency on the Tree Table widget. In the release notes for v4.0.0, Siemens specifically mentions that the Tree Table dependency was removed, and the pages that previously used the Tree Table are no longer used in the new version.
I would recommend updating the Teamcenter Connector Toolbox Samples to the latest version that matches your Mendix/TcConnector versions rather than trying to fix the old Tree Table widget in the sample app.
One important point is that the current Toolbox release 4.0.x requires Mendix 11.12.2. Your app is on 11.12.0, so I would first upgrade the app to at least 11.12.2, and then update the Toolbox Samples and TcConnector to their compatible versions.
If upgrading the Mendix version is not an option, I would keep the existing TcConnector/sample versions instead of mixing the newer Toolbox with MX 11.12.0.
So the recommended path would be:
MX 11.12.0 → MX 11.12.2+ → update TcConnector → update Teamcenter Connector Toolbox Samples
This should also avoid depending on the legacy Tree Table widget.