disappearance of members
 

The recent period and I have a problem missing members and visitors abruptly.
For example, watching the number of members 70 and 300 visitors, and then disappear and become for example, 10 members and 4 visitors
I followed this way but did not succeed
Check the following usergroup permission is set to yes for each group:

AdminCP -> Usergroups -> Usergroup Manager -> Edit Usergroup -> Usergroup Options -> Viewable on the Memberlist