I figured out what was happening. Whenever I play RPGMaker games, I play with just my left hand because numpad 0 works as a cancel button and numpad enter as the confirm button. This works fine in both MZ and MV games, but for some reason, it breaks in VX Ace games. The X key still works as the cancel button fine. This was happening in the Phantom Thief demo as well.
The weird thing is that numpad enter still works as the confirm button all the time, and the numpad 0 worked for a bit at first and then only X worked.