I have ticketed this with the server folks as it appears to be PHP related (and in some way related to the app integration, though the server folks won't know anything about that). It seems that the message is sending despite the error which suggests it is an alert or callback error but that is all I have at the moment. I will update when I have something back
The messages are definitely sending. Server folks said it is the app that is causing the problem (which the error content does support). The app folks are looking into it but I suspect I am going to have to submit their fix to apple for review so please bear with us. The messages are sending - the error I believe is about the notifications being sent (or not sent) to the app. If you just move on like the error never happened, the messages work as they should. I know it is annoying - I am working on it but it may be a few days!