I am running the Beta v7 721. You can see in the example below the radius is set to .5. Each time you change the radius you must enter the number and hit “Enter”. You can then change like I did to .125" and hit “Enter”. The third corner is changed to .125 radius. If you just enter a number and do not hit enter you continue to get a .5" radius.
I drew a square 3.5" x 3.5", selected it, then selected the Corner Tool. You see it says I have 4 valid corner.