Why am I getting different results with the Input System?

I'm a complete Unity noob, just trying to figure out how to use inputs to move the player character (aka a capsule object). After looking at the docs a bit, I decided to learn the newer Input System instead of the older Input Manager because it seems easier to use and makes cleaner/more readable code. I did the "setting up the input system" tutorial which first teaches you how to use the default input setup, and then teaches you how to make a custom one.

My area of confusion is that the default inputs behave very differently compared to the custom ones I set up during the tutorial. With the custom inputs, when I use WASD to move the player capsule, it slides along the ground without changing orientation; if it does change orientation after hitting something else, like if it falls over, I'm still able to move effortlessly with WASD, the capsule just kind of slides around on its side. But, with the default inputs, instead of the capsule sliding around in its entirety, it will kind of tip over if I press W, and once it's fallen down it can't really move back or forwards. If I set the speed high enough I can get it to flip end-over-end along the ground. All my scripts are exactly as they appear in the tutorial.

Can anyone explain to me what's causing the different behavior? I want to be able to use the default controls but I just don't understand how they're supposed to behave.