Stickers not working in Messages app on Mac mini

Stickers works fine on my iPhone Pro Mac running iOS 26 but will not work on my Mac Mini running OS 26. I am signed in to the same Apple account on both devices. I have tried signing out of Message on the Mac and back in again (using the same Apple account) and restarting the Mac without any change to the problem. OS's on both devices are up-to-date. I have an iPad Pro running iPad OS 26 and stickers runs fine there. What is the problem with the desktop Mac?

[Re-Titled by Moderator]

Original Title: Stickers in messages app