Dynamically sum column values by row based on slicer

Matrix visual is working as expected, however does not display the information quite like I'm desiring.

I'm working with a custom 3D visual (I'm in the architecture field), so I'm thinking it may be a limitation with that. I'm not sure on etiquette for sharing pbix files with custom visualizations...I've reached out to the author to ask.

In the meantime, I'm hoping to mimic the function of the subtotal column in the matrix visualization to feed to this custom visualization I'm using. I needs A NUMBER to properly display information (measures apparently don't work). I've tried creating a custom column in my table to sum all required values. This method works, but it is static. I'd like to be able to look at any combination of conditions. 

For context we are creating a 3D "heat map" of high priority spaces to renovate/remodel. See attached screenshot. The "Values" field in the visual currently will display the first value in the list of metrics, but I'd like to get the subtotal column number from the matrix visual. Any ideas?

link to a video of the custom visual I'm using: https://www.youtube.com/watch?v=jyud72ZklZY&ab_channel=ProvingGround