Unable to navigate up and down in the code block

Summary

When pressing up or down, the cursor jumps out ofthe code block

Steps to Reproduce

1. Create a page
2. Add a code block macro
3. Insert a text in the macro
4. Add a new line and add another text
5. Use up and down key to navigate

Expected Results

Cursor goes to the next line

Actual Results

Cursor jumps out of the code block