I have a similar issue also. I have Twitter and FB set to auto-post but as of this morning, only FB is auto-posting and twitter isn’t. Using the manual “post now” button works fine for TWT, as does a test tweet by my developer from the Snap settings.
Through trial and error, it seems that the plugin is only allowing an auto-post to one social media account, as I’ve just tried a post with TWT auto-post ticked, and FB unticked. That worked to twitter but when I tried again with both ticked, only FB posted.
I’m also wondering if something has gone awry from the overnight change in Twitter from 140 characters per tweet to 280?
Any help would be greatly appreciated.