Down arrow key does not work.

Up arrow key works.

Both shift+down arrow key and ctrl+down arrow key work.

Only the simple down arrow key does not work and I cannot move to the block or line below.

Does anyone else have the same symptoms?

I searched and found someone else with the same problem. The up arrow key did not work for that person. However, he created a new graph and it solved the problem. I solved mine in the same way. I moved from the old graph. I will leave a question for anyone else with the same problem. Thank you all for looking at this.