Operating system: Darwin-19.5.0-x86_64-i386-64bit 64 Bits
Graphics card: AMD Radeon Pro 570X OpenGL Engine ATI Technologies Inc. 4.1 ATI-3.9.15
Broken: version: 2.83.1, branch: master, commit date: 2020-06-25 09:47, hash: rB8289fc688b3e
Worked: (newest version of Blender that worked as expected)
Short description of error
When the Units are set to Millimeters the Radius dimensions show as 1,000 times bigger, so 1.5mm shows as 1500mm. All other units show as should. (Although I think the same problem is occurring with the length of the Arc)
Exact steps for others to reproduce the error
Set the units to Millimeters and measure a radius using Measure it tools Add on.