If face detection never works on any images then there is an issue with GPU compatibility or Photoshop’s ability to use the GPU. Face detection is done on the GPU.
In Photoshop, please go to Help>GPU compatibility. Are there any warnings? If the GPU is compatible, it could be that the driver is old and needs updated. This screen should let you know if anything needs addressed on the GPU.
Also, please reset the Photoshop preferences. Than is done under the Preferences General section. Select the reset preferences on quit button. Then restart the entire computer. Then try again. I have seen corrupted preferences file cause the face detection to no work.
Also, another thing to check is under the Preferences and the performance section. Make sure it has the correct GPU listed. I have seen before where Photoshop ignors the dedicated GPU and reverts to using the integrated GPU on the CPU chip. So it may be showing it is using the Intel graphics instead of the dedicated Nvidia card for example. In the Performance section, it will show which GPU photoshop is using. Also, make sure it is checked on. If it is off the face detection won’t work.
Let me know after you have checked the GPU compatibility and reset the preferences.