I've got data on patient falls in one data source and patient days - sum of all days patients were in the hospital - in another data source, and a metric that is "Falls with Injury per 1000 Patient Days". I found that changing the date from a discrete date to a continuous date caused Tableau to not display marks when there were no falls at the beginning or end of the displayed time period. In the following image on the left (rates and fall totals are grouped by unit), there's a discrete date with 144 marks displayed. On the image to the right, the only change has been to a continous date and five marks are missing, one at the beginning of the top row, one at the end of the second row, and then at the beginning and two at the end of the bottom row. The table calculation is at the bottom of the image.

Anyone have any ideas why? I'm guessing it has something to do with the discrete date creating headers and Tableau padding out the data, but I definitely don't know this area well enough to have any certainty about my guess.

Jonathan