Chats scrollback not accessable on a vertical screen.

I have one of my screen vertical so 1080x1920 rather than 1920x1080. This causes an issue with the Chats feature where if the last few messages are short, it doesn't fill the screen and therefor the scrollbar isn't active. This has the impact of not allowing me to scroll further back in the conversation. I've included a screenshot below showing an example of the problem.