Disable Studio Mode, and run in standard.
Studio Mode is more meant for switching into if you need to edit an upcoming scene without showing it on-stream, or if you have a dedicated technician just handling OBS operations.
If you need quick-toasts, you can also create an 'overlay holder' scene and add it to all of your other scenes, add your toasts to the holder-scene, then hotkey the source visibility in that holder-scene. Changes made to non-active scenes are instant. This also means you will not be able to edit any of these sources off-camera during a stream... since the holder-scene is never going to be 'active' (even if it is included in the active scene) any visibility changes, moves, adds will be immediately visible on-stream.