Hey Shayne,
I'm unable to replicate the issue you're experiencing. Did you manually add the 5 selections to the Default Value column for the ParentFullName field? If so how did you add them, did you simply type them in?
If you haven't done so already please try the following: Deleting the ParentFullName row, save the web form, refresh your page, then re-add the field, then let me know what happens.
- Ashur