Engineer default blueprint for tanks randomly resetting back to kodachi

I normally have it at welder, but sometimes when I start a new game, I notice it got set back to kodachi. I look at the setting for the default state and the setting resets back to kodachi. This has happened multiple times recently. I'm not exactly sure when this occurs, since I only notice it after I start a new game with the engineer commander. It's possible it might not be tank factory dependant but I can't tell since I'm not really plopping anything else.