Hi @patrick_culbert,
I have created a new assignment named "This is a Final Assignment". I then exported the gradebook to a CSV file, opened the gradebook in Microsoft Excel, entered values into its column, and imported the CSV into the gradebook. Below is a screenshot of what Canvas showed me. You can see that Canvas found the values that I entered.

I then created a second assignment called simply "Final" and repeated those same steps. Below is a screenshot of what Canvas showed me. You can see that Canvas found the values that I entered.

Based on my testing, I have not been able to duplicate a problem.
Have you reported this directly to Canvas Support?
-Doug