I am not sure when this starts happening, I have been trying to keep an eye on it, first 100 turns went fine, I was getting designs for the Gunboat and the Gunboat-P (Prototype) I think as soon as the Gunboat-L appears the auto generated designs stop making the normal Gunboats and Gunboat-P's then it start making Gunboat-L's but it does not obsolete the old ones. See screen shot. Save game attached also.
I think it has something to do with unlocking the Kinetic Augment line of components. Seems like the names and designs are getting named Gunboat-L (regardless of what they should be) due to having Kinetic Augment's on them. Seems odd this only happens with Gunboats and none of the other designs (which I also added aguments too).
If I decide to obsolete any of these designs myself (to clean the list up) they game stops making any more new auto generated designs for Gunboats.