Grammarly is a popular browser extension that allows you to get grammar tips. It works by modifying the websites you visit to show you grammar suggestions.
Grammarly has been found to corrupt the merge tokens in Fuse. If you use Grammarly, we will alert you when you open the email builder so that you're aware of this problem. The problem occurs when you load Grammarly in a full screen window and implement the suggestions it gives. At this time, it will format your email as normal, but behind the scenes, it corrupts the merge tokens resulting on nothing being merged in your emails.
To disable Grammarly - click on the extension and uncheck "Check for writing suggestions on fuse.agencyrevolution.com."