The tracking axis, the X axis in a 2D display and Z axis in a waterfall and colormap, has always been shown in increasing order for run ups and rundowns. This has changed in Simcenter Testlab 18 with a new feature. You can now right click on the tracking axis (X axis in 2D display and Z in waterfall and colormap displays) and select reverse.
Here is a slide from a What's New presentation. You can read what's new in Simcenter Testlab rev18 and view presentations on the new features on the Global Technical Assistance Center (GTAC) under Documentation for Simcenter Testlab. Here is a link, you can click on the rev18 tab at the following https://support.industrysoftware.automation.siemens.com/docs/simcenter/simcenter_Testlab/.