Gradings Changing to Feature Lines Instead of Staying Grading Objects

[aspencer.226869]

We have been using grading for years to tie fill & cut feature lines back into the existing ground surface. Mostly use grade to surface. No major issues through the years.

Now we have a model file with Finish Grade surface and Existing Ground surface. The file is pretty big (12 MB) because it is a big project.

We have not worked in the model file for a couple of weeks. When we got back in the file to modify the grading, all the grading objects have converted (exploded?) into feature lines with multiple vertices.

When we create a new Grading with Grade to Surface, the new grading immediately converts to feature lines with multiple vertices. It does not exist as a grading object.

Any idea what is causing this and how to fix it?

Thank you in advance for your help.
Arthur Spencer

[Nick Antonov]

Try to Audit the file, I experience lots of corruption(errors) while Grading and when I have quite complex layout. Sometimes Infill does not want to pick the closed feature line in the right site, after Audit it sorts it out.
Auditing in most cases fixes the problem, but I will suggest Save As separate file and then try it.

AUDIT->Enter->Y>Enter