I don't know if this is with Pages or Keyboard Maestro. I suspect it is a Mac-side bug.
In Pages, I have a macro using the Menu Selection action that selects the window menu. This opens the window menu with no items selected. I can use the cursor or arrow keys to select a menu item or add modifier keys to jump through menu sections. All good!
However, if I activate the Menu Section action a second time before selecting an item or even after selecting an item (so the item is highlighted) and the selection isn't executed, then the selection highlighting is removed and the app locks up requiring a force quit.
MacOS 14.2.1 Keyboard Maestro 11.0.2