Unfortunately, a restart does not help. I've had this problem for a while and it's starting to bother me. Could it be because my theme is created for an iPhone 12 Max and I only have an iPhone 12 Pro?
Thanks for getting back to us. Are you using live preview to view the design or you're opening the link on the browser? Does that happen with all the files or with this specific file?
If possible, please share the XD file with me over a private message so that we can investigate at our end. In order to share the file, you need to upload the XD file to a shared location such as CC or Dropbox and share the URL with me over a private message.