move right left doesn't work

Calc 5.4.1.2. The left arrow key doesn’t move focus to the next left cell. Instead it moves the page one cell to the left, without moving to the next cell. I have checked the tools>customise and it says left moves left. Same goes for the right, up, down arrow keys.
Is this a deliberate change, or am I doing something wrong?

What happens with the arrow key in other applications? Perhaps your ‘scroll lock’ key is on