As @baggepinnen says, try
rlocusplot(sys2, xlims=(-40, 10))
Part of the rlocusplot recipe (in src/root_locus.jl) is the line,
xlims --> (max(-50,minimum(redata) - 1), clamp(maximum(redata) + 1, 1, 50))
This finds the limits of the calculated root positions as the gain K is swept from 1e-6 to 500, but unfortunately this doesn’t include the location of the zero in this case.