Slack Add-On Mentions Not Working

When creating a message to be announced in Slack, we’re noticing that the @mentions are not working. We have an onboarding form that is supposed to announce to the whole team on our #general Slack channel that a new sale has been made, however, while all the GF merge tags and Slack emojis are working fine, the @channel mention in Slack does not. It just gets printed as a basic string of text instead of being a Slack mention.

Has anyone else run into this or know why this is?