It is hard to tell without zooming it, but the red dot is actually a "D". So, a bug with a "D" gets us "Debug"
Debug ladder files will only download and execute in the RSEmulate 500 emulator program. You will see them offline, but they do not execute online with a physical CPU. I don't remember if they are displayed online with a physical CPU. I don't think they are, but I can't say for certain.
OG