Ok I tested it and this is a bug in RPG Maker's input manager, which freaks out if you move using the numpad (with NumLock on) and press shift at any point, because that changes the press from, say, numpad 8 to up arrow, both of which mean moving up, but only one gets "released" and the game thinks you keep pressing up forever. I play roguelikes a bunch so I just used the numpad out of habit, I might not be the only one. Changing the sprint command to another key would fix it.
you can change the keybinds in the config menu! just hit f1 and go over to the “keyboard” tab. for reference, “A” is the sprint input















