* Inspect the Dimension Properties: * Double-click on the first dimension to open the text editor. Notice the dark solid color background behind the dimension text. * This indicates that a background mask is enabled for this dimension. * Check the Background Mask Settings: * Select the dimension and go to the Properties palette. * Under the 'Text' section, find the 'Fill Color' or 'Background Mask' setting. Ensure it is set to an appropriate color (e.g., the same as the background). * Compare with the Second Dimension: * Double-click on the second dimension and observe the absence of a background color during editing. * In the Properties palette, confirm that the 'Background Mask' is either disabled or set to 'None.' * Adjust Settings if Needed: * If you want both dimensions to have a background mask, enable the 'Background Mask' for the second dimension and choose the desired color. References: * AutoCAD Documentation on dimension styles and background masks: Dimension Styles