Greetings KathWright,
You’re most likely running into an issue that cropped up in EndNote X8.1, where the reference preview panel doesn’t update dynamically. This issue has been reported to Development and appears slated to be fixed in the next EndNote X8 update. For now, you’d want to click off the library record after making a change, then back on to that particular record to view the updated reference preview panel.
Please let me know if this works for you.