Cannot navigate in any page with keyboard without mouse click

Currently in Bitbucket Cloud, navigating within a page with the keyboard (page up / page down) does not work until there is a first mouse click.

Steps to reproduce

1. Click "Pull Request"
2. Use keyboard to navigate up/down the page and there is no response
3. Click on the page and try navigating with keyboard and it works fine.

It would be useful to be able to navigate in a page using keyboard instead of requiring a mouse click first.