forced timezone set
There used to be a setting to forcefully set the timezone (something like that - wpmltimezone_set option in the wp_options table). I noticed you have made some changes in recent version updates regarding the timezone issue and it seems the configuration setting is gone. But, if you had that set to true in a previous version, it is still set that way in the newest version and it screws up the timezone completely. Can you verify this and comment?