Want to confirm what alexblajan posted 3 weeks ago:
"@Jesin A if you modify your OPCache configuration as follows you will see that it will work better.
opcache.revalidate_freq=0
opcache.consistency_checks=1"
I have the same configuration, and have been experiencing the same problem with W3 and the OPcache (changes in W3 admin not showing up right away - as well as a MaxCDN error message that would not go away). Updated the setting with the two lines recommended, and problem resolved.
Thanks for posting this alexblajan!
I uninstalled and re-installed W3 twice thinking something was awry, but this was the problem.