It's hard to say what's going on without seeing some sample data or a packaged workbook. I have two thoughts:
1. By default, Tableau aggregates the measures that are in the view, so [Sales] becomes SUM([Sales]), etc. So you might have SUM([Sales]) and SUM([Profit]) in the view. However, if you set up a calculation of [Sales]/[Profit] that's going to be calculated on each row in the underlying data, whereas SUM([Sales])/SUM([Profit]) would be what you'd likely expect since that would be calculated based on the dimensions in the view. I set that up in the attached workbook.
2. If you have numbers that are set to display as integers or as #K, #M, etc. and you have a division calculation that results in values smaller than 1, 1K, etc. then Tableau can end up rounding and displaying zeroes, so you'd have to appropriately adjust the number format for that measure.
If neither of these ideas work, post a packaged workbook with some sample data and we'll figure it out.
Yes Johnathan, the solution was definitely point 1. Thanks!!