Message/email list view not displaying properly

I’m trying to get my email list layout to maintain this format:

However, when I drag the bar to the left (so the email pane has more room to see the whole email), it compacts the email list view and ends up looking like this:

This seems to be a bug, as there is more than plenty of space to maintain the first format. When I click on the border,  you can see the preview line is way to the left - as if there’s a ton of padding/margin where it shouldn’t be, as seen here:

Note the line under the “reply all” button.

So, anyone know how I can fix this?

Thank you!

By default, when the message list is less than 600 pixels wide, it will revert to compact layout. You can change the settings in Menu > Tools > Settings > Mail > Read > Message List.