Moving from sandbox to produciton. Sandbox was still using older dev tools. On Production set up new dev tools for TBA. fetch theme, update and push to production, New Version shows up in Extension Manager and activates fine. fetch extension, update and push, CLI says everything is successful but Extension Manager does not show the new version of the Extension. In summary, I am unable to see my newly deployed extension in Extension Manager with the new dev tools, even though I get "success" message during deployment

Look for the record SC ExtMech Extension associated to your extension and delete the Target version, after tha the extension should be displayed on the list.

I will check it out!