Dunno if it's something caused specifically by elevated rials or not, but when train is on elevated ones, construction wagon does not transfer items between wagons.

Will look into it when I get home from work. Thanks!

One quick thing you could try for me is being in the wagon when it's trying to do stuff. It is a bug I found in the old mod that only sometimes happens

After some early research, it seems to be an issue with how the entity is detected while in motion. still working on it!

Fixed!