Editing Spot Elevation Breaks the Slope Callout Tool
Issue
You placed two Spot Elevation callouts and can use our Slope Callout tool to calculate and label the slope between them. However, if you edit a callout, you're no longer able to use the Slope Callout tool for automatic Slope Callouts between two Spot Elevations.
Cause
Your Callout Light Text Style has been switched in this drawing from the one set in your Preferences (such as Arial) to a different version of that font (e.g., Arial CE or Arial TUR), likely as a result of corruption in your drawing.
With the Text Style changed, when you edit the Spot Elevation's MText, CAD adds a font formatting that can be seen in the Properties panel, as pictured to the right.
This formatting is blocking the Slope Callout tool from reading the elevation.
Solution
You can resolve this issue by editing the Callout Light Text Style and changing the font back to Arial (or whichever font your office standard calls for).
How to edit our default Text Styles
New Spot Elevation callouts should now edit without the formatting being added.
You can sometimes clear the formatting in existing callouts where the issue has already happened:
1. Double-click the callout to open the Text Editor context ribbon.
2. Highlight all the text in the callout.
3. Select the Remove all formatting option from the pull-down menu in the Formatting panel.
Keep in mind that this method does not always work, for reasons that are currently unknown. If this method doesn't work, you'll need to place a new Spot Elevation instead.