I've got the classic tree-farm setup, with an advanced smelter and solar panel and engine, etc. As my cart moves around the track I have setup, it frequently replaces the track in front of it, or the track it's on with saplings, making it unable to move.

Oh thats a strange one, I will take a look. What type of saplings are you using?

Not sure if you saw my question: What type of saplings are you using?

Humm, what upgrades do you have on the cart? and also what version of Steve's carts are you using?

I've had the same thing happen with a cart on my server. Same version of SC, pretty similar cart setup, and also oak wood. Using Forge 1.10.2-12.18.3.2185 on both server and client. Happy to provide any other info or load up a dev build as needed. This morning it ate a track after a turn and replaced it with a sapling where the pattern shows a sapling might have gone. While writing this post, it ate another track piece on a long straight track and didn't replace it with a sapling.

I need a way to reproduce this, I have been running a tree farm on a world for a few weeks and not had this happen

Others on my server solved the issue by placing stone under the track. The map is pretty dead at this point, so I'm not sure I can get much more info for replication. This may have been resolved in the last month, I haven't followed the repository changes.

Ah right, ok. That might atleast me try and track the issue down.

ah, ok. That might be helpful to know.

This still happens on ATM2. Vanilla saplings, range extender, 2 smelters, reinforced cart, Side Chests and Coal Engine. You let it go then come back to it off the track on a sapling placed where a track used to be.

Also I don't think it happened before I added the range extender but I could be mistaken. Maybe others can verify they used one too.

Reproduced this in 1.11.2-2.3.0.22, modules on the cart are: Reinforced Hull, Coal Engine, Hardened Wood Cutter[0%], Side Chest, Top Chest, Internal Storage x2.

Rail setup is like this, 3 blocks between all of the set amount of rails.

The stone preventing it from happening is likely because the woodcutter checks what's below where it's planting, but doesn't check if there's something in the block it's targeting to plant.

Seems my issue is caused by a mod planting saplings when they would normally despawn on the ground as the floating entities. Gonna go bug the ATM2 dev instead.