I am having an issue with Microsoft Word and navigating cross references. I have inserted a cross reference to a chapter header and it works. When I use the alt+left arrow combination, this takes me back to the cross reference as expected. However, it also replaces one the characters in the cross reference with a diamond shape, depending on where the cursor is.

Checking online I find that alt+left arrow is used for going 'back' and also for inserting the diamond shape. Is there a way to stop Word inserting this shape every time I navigate back from cross references?