Also, like Le chef Isidore, nothing helps.
I did a clean WordPress install, with only this plugin, after a couple of time, i have a white screen of death, wordpress didnt work anymore with db? have no access to admin panel or else.
But – when i go to my webspace via ftp, an rename the plugin so wordpress doesnt find it anymore, all works fine.
But is only with the PRO addon, not with the Free version, i know for PRO please contact support, but with Timezones and more, it take to long with e-mail support at all.
An then, here come the, deactivate the plugins, clear cache, pp…..
BUT it is a clean install!