PROBLEM:
When you try and add dimensions in an elevation or section you can't. You get a circle with a line through.
CAUSE:
Revit requires elevations and sections to be EXACTLY perpendicular to grids, and you can only dimension objects that are EXACTLY perpendicular to a section cut.
Even if they are out by 0.0000000012mm you will get errors and crashes:
SOLUTION:
You will need to try and rotate the elevation or section so it is perpendicular.
You do this by rotating the elevation or section reference.
See SECTION IS NOT PERPENDICULAR TO VIEW for sections with this problem.
See ELEVATION IS NOT PERPENDICULAR TO VIEW for elevations with this problem.