Issue with Layer Movement in After Effects

I am unable to move layers up or down in the Timeline panel using keyboard shortcuts. Typically, the shortcuts Cmd + Shift + [ (Mac) or Cmd + Shift + ] would allow me to rearrange layer positions in the stack, but in my case, they only select layers instead of moving them. I have tried using both the keyboard shortcuts and dragging layers manually, but neither approach resolves the issue. I've also ensured that I'm in selection mode, made sure I'm focused on the Timeline panel, closed and re-opened AE, and restarted my MacBook.

Unfortunately, none of these methods have worked, and I’m still unable to move layers within the Timeline panel. I don't know if this is happening because I'm doing something wrong, or if it's a bug. It's my first week using After Effects, so any guidance would be appreciated.