Porkchop plot
http://mars.jpl.nasa.gov/spotlight/porkchopAll.html
Is MJ doing the porkchop plot or are you using a different mod like this one
https://kerbalstuff.com/mod/268/Tran...ndow%20Planner
Or just the old website one.
MJ tends not to be so great for a number of things (at least when I last used it which was several versions ago). It tends to be good to idiotic with auto landings, its control inputs are super twitchy (all or nothing control inputs) which can be a huge problem for launches in realistic atmospheres, and it can be down right terrible at plotting intercepts. Worst was for planetary intercepts where the program would sometimes decide to wait for a few game years to make the transfer.
But maybe some of this has changed as it has been a while since I used it last.