Fractional scaling

Hi! Just installed F37 beta on 2 different thinkpads (6th and 8th gen) and typed: gsettings set org.gnome.mutter experimental-features "['scale-monitor-framebuffer']" Logged out. It's working fine on the 8th gen but not on the 6th gen. While both have the scaling available at every 25% increment under Gnome settings - Display settings, selecting anything else than 200% doesn't work on the 6th gen. The apply button becomes dimmed and it says "This could be due to hardware limitations". The same feature was working fine under F36. What should I look at now to resolve this? Thank you. Fred