Why is the Dawn theme preventing pop up notifications for free gift additions?

[woolrex]

Hello,

we want to use the kaktus app to automatically add a free gift to the shopping cart.

Unfortunately, it doesn't work. The ATC is redirecting directly to cart page instead of pop up notification. Despite it was set (see photo).

The app support told us it must be caused by theme settings, so they can't help. Any help here?