ruler tool in V21 does not measure angles
Select the ruler tool and drag out a line.
Hold the Alt key and drag out a second line from the first
This should display both lines and the angle between them should be readable in the options bar:
CC2018 works correctly
CC2019 the first line vanishes but the points remain and the angle is displayed
CC2020 (v21.0.1) both lines disappear when attempting to drag out the second line
System : Windows 10 v1903 build 18362.476 GPU NVidia GTX1080 driver v 436.15