Constant variable in the graph is not updated

Which version of node-red-dashboard are you using (look in Manage Palette)? If you are not using the latest then upgrade to latest. I see you are also using an old version of node-red, that is not likely to be the problem here but it would be a good idea to upgrade when convenient.

For future reference see this post for how to share your flow here - How to share code or flow json