Greetings! Recently, since we updated to 3.6.16 it seems like but I’m not positive, when we import subscribers to a list, the counts are not updating until we log out and then log back in again. It seems like a cache issue, but I can’t figure out where to clear a cache to get it to update. Or if that’s even the problem! We’re running on a GoDaddy VPS server with Plesk. Zend OPcache is enabled.
Has anyone else run into this and fixed it? What should I do? What other info can I provide to help troubleshoot?
Thank you for your time and attention. 
@Excelsior Yes the counts for each list are cached for a random period. The only sure way to clear is to logout and login again.
This was introduced in release 3.6.11 because of performance problems with very large lists (millions of subscribers, I think). You could make a simple modification to the phplist code to set the cache timeout very small or 0
in file lists/admin/actions/listmembercount.php line 62 is
$cacheTimeout = rand(900,15000); ## randomly timeout the cache
you can change that to 0 which should force the counts to always be calculated
$cacheTimeout = 0;