The preview slides for your custom blocks are displaying the incorrect True Colors, or the colors in your slides are not matching the blocks. You might notice this issue with plant symbols or site object blocks that you customize.
Here's an example of a customized plant symbol block appearing in a different color as placed in the drawing vs. the color that shows up in the symbol's slide in the Plant Info dialog box:
The color will also look different in the symbol's slide in the Planting dialog box.
The AutoCAD Slide system only supports 256 colors, so True Colors are rendered to their nearest approximation – which is often vastly different from the color as it appears in the block as placed in a drawing.
This issue is an inevitable quirk in working with AutoCAD. If you create custom symbols using True Colors, you'll need to be prepared for some color variation between your preview slides and the corresponding blocks as placed in drawings.
We've gone through a tremendous amount of engineering in creating literally tens of thousands of color symbols as part of our Color Render feature. Rather than having to create all these symbols yourself, we recommend using our color symbols if possible.