If you're using a Windows machine with a high resolution, small display, or a display with a high DPI setting, you may notice Photo RAW doesn't scale properly, and that certain parts of the program are hidden.
To adjust the program to your display, right click on the icon you use to launch Photo RAW and select Properties.
Click the Compatibility Tab, then 'Change high DPI settings':
Check the box next to 'Override high DPI scaling behavior' and use the dropdown box to select 'System':
Click the OK button on both of the open Properties windows, then relaunch Photo RAW.
If you are still having display issues after trying the above steps, please also see this knowledge base article from Microsoft.