That is very unusual. If you go to the practice form, click the extension icon (or right-click and select "Add rules for this page"), and click Generate Autofill Rules button, you should get the message "No fields have been changed". The fact that you're getting the message "Done" tells me one or more of the fields have changed between the time the page loaded and when you clicked on the Generate Autofill Rules button. Is there another extension that is changing the field values? Try this:
1. Disable all other extensions
2. Disable the built-in Chrome autofill feature
3. Load practice form
4. Enter something in the Full Name field
5. Select "Add rules for this page"
6. Select a new profile
7. Click Generate Autofill Rules
8. Open Autofill Options
9. If not already there, go to the new profile you created in step 6
Do you see a rule for Full Name?