It's the second time I have attempted this scenario and the same thing. Actually two different scenarios but oil.....
On the wagons, the decoupler should be in front of the right hand side wheel. It is a small lever connected to the coupler. On the locomotive, the lever is next to the staircase (it is closer to the wagons than the stairs. Hope that helps!
Yes I have used them in real life. The game prevents me from clicking it. I'll try again..... I could uncouple wagons in the massive yard in Tees Valley..... in game. I'll try a scenario with car carriers.... The screenshot tells you all you need to know there is no uncouple (as in left mouse click or E button) feature. Unsure if it is a game bug or what.
No I mean you aren't looking in the correct place. You have to look next to the front right hand wheel of the wagon to uncouple (and similar for the locomotive. In the picture you are looking directly at the coupling. Ooh I didn't know you had real world experience!
I was looking everywhere yesterday but you're right! I saw the lever and I wonder now if I did hover the mouse over it or not. Anyway today it works! And thank you I now do not know if I did. But I'm sure I tried everything. Anyhow thanks!!