Single scatter chart w/ dynamic XY axis

Hey Jimmy,

Please see attached pbix

My original plan was to be able to:

1. Select what Sections to compare (multi-select slicer for Section 1, Section 2 and Section 3)
2. Select what metric (column) to plot on x-axis (single select slicer for thickness, mass, intrusion etc.)
3. Select what metric (column) to plot on y-axis (single select slicer for thickness, mass, intrusion etc.)

So, the goal was to plot, for example - mass vs intrusion for Section 1 and Section 2

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After spending some time trying to figure out a good approach I ended up transforming my data as follows:

1. Create a new source w/ all Sections combined and respective columns aligned, and Add a column to index each unique row
2. Duplicate this Table and unpivot all metric columns - Combined_unpivoted_X
3. Duplicate this Table and unpivot all metric columns - Combined_unpivoted_Y

Now I'm able to dynamically choose what sections to compare (using multi-select slicer) and what Xvalue and Yvalue to plot (using the single select slicer), but when I plot Xvalue vs Yvalue the scatter chart says 'Can't determine relationship between fields'.

I have tried defining relationships, but it still won't plot Xvalue vs Yvalue, and I'm not sure why!

In the attached file - you'll see I'm able to pull all the necessary data - just not able to plot it!

I'd appreciate if you could take a quick peek at it and let me know if I'm missing something. 

Thanks!!