Here are the steps to my problem:
1. I double click a cell in the bill of material to edit a part's custom properties.
2. After editing the cell or when I leave the cell without editing it, a letter and number appear (example: B1, B2).
This number and letter that appear puts this value in my part's custom property at the part level: <ZONE ViewId=157>
Then I have to manual go to the part and remove this string of text everytime I edit a part custom property within the bill of material on my drawing sheet.
How do I stop this from happening?