Hi @TDK_Long,
I'm fairly certain this is a rounding artifact from Excel's export. Looking at line 1207 in the .csv file, there are only 3 significant figures in the X column (1.03E+01 in Excel = 10.3 in JMP). I'm assuming your original Excel file has more significant figures, but is only displaying 3 of them, and Excel is exporting the 3 figures/digits into the .CSV file. This will cause the intermittent dots in JMP, because JMP doesn't have this information that Excel isn't exporting.
If this assumption is correct, then changing the number format in Excel before exporting will allow more detail (a smoother line) in JMP.