The count of active threads is added by the Listeners when they write the sample details to the log. This works OK for local tests, but does not work for remote tests - they will show the local active thread count, if any. The count probably needs to be saved with the samples. [When fixed, update the comment in section 14.6, Listeners]
Fixed in SVN trunk r577514
This issue has been migrated to GitHub: https://github.com/apache/jmeter/issues/2018