Review on 🔧 Gladiator Joe VESA Bracket Adapter: Compatible with Acer S200, S206, S220, R221, G226, S230, G236, G247, XG270 - Laser Cut, 100% Made in North America by Mary Hovatter

As this is specific to an Acer monitor this is normal but the mount is disabled when multiple monitors are installed on the arm. It just didn't work at all. Which is disappointing. If it's the only monitor you have, it might work, but if you want to set up multiple monitors, there's no need to line them up.