And, that confuses me...
So, you clicked on Standard view, and the window moved to Chrome web browser?
All are Google, but what value is the Mail for GMail app, if you are simply using Chrome?
I did see a couple of different posts when I was searching around for this, that the Mail for GMail app started acting up a few days ago for others, as well. Maybe you just need to be patient - might fix itself in the next few days.
Maybe just business as usual for Google...