Are you sure you are using WordPress built in “Schedule” functionality and not some third party plugin or service to schedule your posts? Some plugins like “Publish to Schedule” are not compatible with SNAP.
Our plugin posts to all configured social networks at the time post goes live. Technically speaking our plugin is hooked to the event of changing post status from whatever to “Published”. This event is triggered when you hit “Publish” button, when you post on your site from email, when you publish post from your iOS/Android Device, when external plugin correctly published new post, and when scheduled post becomes live. Some third party plugins (like “Publish to Schedule”) change the status of the post to “Published” right when you create it and then just keep it hidden until it’t time to present it. SNAP reacts on the change of the status and autoposts it. Some other third party plugin make post “Published” for several seconds for some internal reasons and then revert it back to “Scheduled”. Again SNAP reacts on the change of the status and autoposts it. Please use built in “Schedule” functionality from WordPress or any third party plugin or service that changes post status correctly.