Does anybody else have the problem with the user profile image size settings being ignored?
If I set user pictures in admin/config/people/settings, and settings like this:
The user pictures are uploadable, but in the user profiles are full resolution, unscaled, as if the 300x300 scaled down was ignored. I checked with a D7 installation and it did the scaling.
Unless I'm misunderstanding you, I'm not seeing what you describe. I reproduced your settings (see image)
Then I uploaded an image with an original width of 1900 x 1900. The image is displayed according to the "Thumbnail" setting under "Picture display style" as expected (see image).
When I inspect the actual file in Structure > Manage files, I see that the image has been correctly scaled to 300 x 300 (see image)