Some users may not be able to view/load the animated or static survey icons on their email due to Outlook settings and limitations. Depending on the Outlook version that they're using, they might see a play icon button or a click here to view the image.
There are three ways to get around this.
You could ask your customers to unblock picture downloads for all messages by adding your domain to their Safe Sender List.
You could switch to a static icon set.
Display colored boxes if images don't load - select this option in the survey Publish tab to add a background color to your survey to make the choices obvious if the images don't load.
The survey icons will look like this when the images don't load:
4. Display text labels under rating images - select this option in the survey Publish tab to add a text link under each of the survey images in case they're not being displayed, or can't be clicked.