When changing the eccentricity to 1 the plotted orbit is still a closed ellipse with apparently eccentricity extremely close to, but beneath 1. The plotted orbit should be open and parabolic.
When changing the eccentricity down to 0.999 the plot reduces in size dramatically, but remains very close to the shape of the open hyperbolic orbit with eccentricity 1.001. This may suggest that it's just an issue with the plotting logic rather than any errors in astrodynamical calculation.
When changing the eccentricity to 1 the plotted orbit is still a closed ellipse with apparently eccentricity extremely close to, but beneath 1. The plotted orbit should be open and parabolic.
When changing the eccentricity down to 0.999 the plot reduces in size dramatically, but remains very close to the shape of the open hyperbolic orbit with eccentricity 1.001. This may suggest that it's just an issue with the plotting logic rather than any errors in astrodynamical calculation.