Intel released a microcode update last December for many of their CPUs. After this update is installed, it will block under volting and it will block adjustment of the Turbo Ratio Limits.
I have never seen a screenshot where the turbo values are all set to 0. Did you update your BIOS recently? It is also possible that this microcode update will be coming to your computer this year via Windows Update.
When the turbo ratios are set to 0, this will disable Intel Turbo Boost which was a feature of this CPU. That is why your CPU cannot go any higher than its default speed of 2.8 GHz. With these ratios locked at 0, there is no way to adjust them higher.
What laptop model do you have? Other users need to be warned.