LOL. Yes, I restarted JMP each time I ran a new set of tests you suggested.
1. Opened the STK Included Maps folder.
2. Copied the two STK_300mm*.jmp files.
3. Opened the JMP User Maps folder. The two STK_300mm*.jmp files were already in this directory. I pasted the two files and replaced the original copies.

4. Closed the STK windows and restarted JMP.
5. Reopened the STK and confirmed that "300mm_wafer" is still included in the Background Maps tab.
6. Clicked Bare Wafer Mapping and selected OK to load the example data set.
7. Repeated the setup of the 5 plots for bare wafer mapping data.
Result: I still see square maps and the Set Background Map settings show Images set to "None."

In previous versions of JMP, there were options in Graph for "Legacy" plots that would allow the builder to build contour plots and import a map as a file. Is there a way I can pull the 300mm_wafer map file into the Graph builder of the Unpatterned Wafer Data mapping tool manually?