Why does Game tab's scale get reset to 1 every time I click Play?

I am working on a mobile game, so I set the screen size in the Game tab to a phone resolution, for eg. iPhone 1334x750 Portrait. I see the whole game screen.

Then when I hit play, the Game tab’s scale gets reset to 1. This causes the view to be zoomed in. I have to drag the scale slider back to the far left eg. 0.29 in order to see the whole game screen.

OR I can drag the edge of the Game tab a bit to resize it which sets the scale to the far left for me.

Then when I stop the game and hit Play … again the scale sets back to 1.

BTW I am using 2018.3.0b6

Seems Unity reset scale to “fit pixels”. Try to change from resolution to appropriate aspect ratio (16:9, 4:3, etc.).