Please upgrade to 2.2 here.
The 2.0 and 2.1 branches are no longer being updated.
Users cannot make themselves invisible in Who's Online Pro
This discussion is related to the WhosOnline
I have purchased Who's Online Pro, but the option for people to make themselves invisible doesn't seem to be working. I've allowed it under the "General Settings" for the plugin but when I toggle the option to "make me invisible" under my profile settings, nothing happens. In addition, the option I've chosen doesn't seem to save properly. Any thoughts?