Add another concern about vertical layouts -- as started here:
To add to that, it appears Alert Coloring doesn't work at all anymore for Vertical layouts. This applies to the old .cspx and new format capsules, when rendered in the Web client.
In v10.5 while in the Windows client only, the vertical-layout alert-coloring still works at intended.
It's a shame that vertical layouts seem so complicated/ unloved. I would say they are an important visual design choice in rather --- at least half of all layouts (well they should be, most people will force stuff into the other orientation due to feature limitations).
While I'm on the topic, vertical layouts also need to have a "column width" feature as well, as that has always been missing as well. I would say a very common use case of vertical layouts is showing maybe 10-20 Key KPIs vertically, and having the Month (or Year) horizontally, to show maybe 3-12 months. Sometimes visually it's just preferable to use vertical layouts. But in most cases, the width needs to be configured manually. To be honest, I'm not even sure header column widths in Vertical Layouts are configurable at all in the web-only design capsules!