Hi! It sounds like you're both seeing that your icons show blank on the canvas, but the icons worked previously and work in new files. To confirm, have either of you updated or changes the version of the icon font that you have installed locally to your machine, or the widget library file? As a first step, you'll want to ensure that you still have the version of both the font and the widget library matching, like in this post:
If they match and the issue only appears when you bring the existing files into the updated version of Axure RP, then would you mind attaching a copy of the file or sending it to email@example.com so that we can take a look?