Hi there Shay and Tony, in v1.8 we have changed the way slightly for how variables are used. It allows more control by the user. Below is a link to our docs Shay R that has additional information regarding variable usage.
https://docs.thoughtly.com/build/agent-builder/variables
The @ system Shay is referring to is not in v1.8, but it may get added back since we have been getting some requests from the community for that. However, the {{variableName}} notation should be working and highlighting green on all nodes.
Shay R Do you have a few minutes to hop in a call so I can help you sort this out, I am not quite sure anymore exactly what you are trying to do and want to make sure I get you the correct information.