This has happened to me more times than I'd want, and I believe it will continue to do so. I'm making monthly, annual, or weekly reports and dashboards. The dates only include the final day of the term. For example, I am now working on a bar chart with a trend line for the 2019 monthly report. In Excel, it took me around 15 minutes to make. However, for dashboards, we are attempting to migrate everything to Tableau. When using discrete dates, the trend line is always greyed out, while when using continuous dates, the trend line is occasionally greyed out. I can convert the dates to continuous because they are in the format DD/MM/YYYYY, however this skews the spacing on the X-Axis. I've been tinkering with it to get it to function, but it takes time. I'm surprised that such a simple thing doesn't function, especially because Excel has been able to perform it for a long time. Is there a good workaround out there? I tried calculating the trend line manually, but I'm not sure how to incorporate the created y=mx+B line. I'm thinking about making a data set particularly for this, but it seems like a lengthy and difficult way to go for something I would expect out of the box. Below is some basic data; creating a line chart in Excel takes around 1 minute; simply click (+) add trend line and you're done.