I am selecting the option to remove the frames from all my icons on the home screen.
I select done but when i go back to the home screen the frames are still on icons. Even though the icons only option is still selected.
For me is greyed out when a theme is applied. Remove the theme and you will be able to activate/deactivate it. But there is no difference (with almost all google apps icons) when the "Icon Only" is set to active.
Android central has something about it in the link below. It is to do with adaptive icons apparently.
Personally I've found the white background on all the google icons so ugly I've removed them from the home screens and quick luanch. I'll probably use those apps less as a result.
The icon frames option is not available anymore in the settings and I have tried the quickShortcutMaker app to take away this whit frames around the apps but it did not work.
I would have not installed the latest update if I had known the option to remove icon frames was going to disapear. My S9+ now looks UGLY.