If you are using Companion to send the messages you might need to check on the version of it.. There was an issue not that long ago where it seemed that the RossTalk plugin for Companion was broken. Some users had posted that they were working around it using the Generic TCP connections method and having to manually create the commands.
You can also test this just using DashBoard and a Custom Panel interface where you send commands using the RossTalk in it.
If your using the Ross RossTalk plugin not companion then I would make sure that companion is not setup to talk to the RossTalk Port 7788 just to make sure it's not blocking other connections. And if possible show some screen shots of what your assignments in the Stream Deck so we can have a look at them.

That is an example of what I use with my Graphite in the plugin and it works fine. Carbonite Black has the same RossTalk in commands and based on the same software.
------------------------------
Les O'Reilly
Director - Switcher Product Management
------------------------------