Matrix variables used as global variables in builds

I am on Drone 0.8.5 and have been using this workflow fine in many projects, but suddenly a project is randomly missing matrix variables when used in deployments. The commands that had the interpolated variables are sometimes blank. But as soon as you restart build/deployment for that failed task, it works.

While I understand that this is a misuse of the matrix build vars, its the only way I have found to define a global variable to be used in multiple steps in a pipeline.

Any one run into this issue?