This is related to a bug mentioned in other reports which were closed. Workflows which are triggered by pushing a tag will run, but they do not appear in the workflows panel in the webgui. To see them workflow, you have to find a job in the jobs panel and then navigate to the workflow from there.
We use tagging for our releases and would like to easily follow their success or failure. This does not appear to be possible in CircleCi or GitHub at the moment.
See Tagged Workflow run doesn't appear in Workflows section for an example of how to reproduce.