There is a small bug in the game when coupling the cars with loco. Sometimes the game after coupling change the order of cabins in loco. For example if you have been in cabin 'A' before coupling after that game would sometimes change it and now you are in cabin 'B'. If loco have option to switch cabin radio(EU07, ET22 etc) try it and check if radio works.
For E186 I have tried the scenario and everything works fine. Check if you have deactivated the second cabin, released spring brake and liveries are coupled fine.