I stored 6 Wooden Planks and 3 Container in the warehouse to crafting 3 cabins.
Because I cannot choose the cabins to craft, I go to the Main Menue and quit the game.
After restart SnowRunner I go to the Cabin craft warehouse, all Wood and Containers are at 0.

Test with the warehouse near the garage, where I can craft concrete blocks/slaps.
I bring 4x cement... go to main menue, quit SnowRunner (nothing crafted).
After restart SnowRunner, there are no cement anymore at the warehose.

Again a test at the warehouse for the cabins to craft.
I store 1 container, left the game as usal, restart, and the warehouse is empty.

Next test:

I put 4 cement in the warehouse near the garage.
I craft 1 concrete plate
In the warehouse are 1 concrete plate and 2 cements to load (says the menu)
I leave to the Main Menue and then I continnue this game (without leaving to windows)
Warehouse is empty... no cement, no concrete plate

Hello @Fratzegeballer
Can you please also attach screenshots or vid for this issue?
Also mention your KSIVA code, you can find it at the bottom of the screen.

@rudeborya
Here's the video. KSIVA: p:436f7

I unload 4x cement at the storehouse
I pointed with the mouse that there are 4x cement in the storehouse
I leave to main menu
I continue this slot/game
I open the storehouse and everything is at 0

Youtube Video

happened to me to,

Yup, I lost 4 containers when quitting and starting the game again. Luckily containers are close to Cabin Factory and the Tayga can go pretty easy and quick on train tracks even winching an extra trailer so dragging 4 containers in one go was done quickly
I wonder if we will be able to use a train in the future. Would be great to use the forklift to load the train and then transport and unload at the destination. I know it isn't the main purpose of the truck driving game but still a great addition to get an even better experience.

@Fratzegeballer Thank you very much for the info provided.