Cura does not allow you to set Flow on Material Profiles for some stupid reason. This patch fixes it.
Tested on Cura 3.6, might not work on other versions.
rm /Applications/Ultimaker\ Cura.app/Contents/Resources/lib/python3.5/cura/Settings/MaterialSettingsVisibilityHandler.pyc
curl -L https://gist.github.com/knoopx/0f600cfdd14863f45f4e90842688e888/raw/MaterialSettingsVisibilityHandler.py > /Applications/Ultimaker\ Cura.app/Contents/Resources/lib/python3.5/cura/Settings/MaterialSettingsVisibilityHandler.py