Radius = MarkRadius not working?

Good morning, all,

Something simple, but … in the attached Rhino 8 file, I am running Radius on a curve between 2 lines with MarkRadius enabled and it doesn’t seem to be dropping the radius. Is this correct?
MarkRadius is not working.3dm (191.9 KB)

That is correct

https://docs.mcneel.com/rhino/8/help/en-us/index.htm#commands/radius.htm

Use a radial dimension to annotate.