Since the bug report seems to suggest you're not using Wayland but have only enabled fractional scaling for Wayland and not Xorg, please try:
gsettings set org.gnome.mutter experimental-features "['x11-randr-fractional-scaling']"
Since the bug report seems to suggest you're not using Wayland but have only enabled fractional scaling for Wayland and not Xorg, please try:
gsettings set org.gnome.mutter experimental- features "['x11- randr-fractiona l-scaling' ]"