Dislikes as in you can't put them in? Does it say something along the lines of "locomotive cannot be smelted" when you try placing it directly into the machine's interface?
Have you added any vehicle grid mods recently? If you have the non-recyclable power armor setting enabled (under Settings > Mod Settings from the main menu), along with vehicle grids, then no vehicles would be recyclable.
This setting is to prevent the unintentional recycling of a power armor with equipment inside of it. Although I could probably change the logic about that...
