Negotiations in GB, game asks for diamonds when I have 2 turns left

[Zinc Tycoon]

In Guild Battlegrounds, why does the system ask for diamonds when I have 2 turns left?

 

[BruteForceAttack]

In Guild Battlegrounds, why does the system ask for diamonds when I have 2 turns left?

You ran out of one or more goods

 

[Lancer]

Along with what is stated above, if you read carefully, it isn't asking for you to pay diamonds for another turn, it is asking for you to pay diamonds to make up on the amount of goods you are short of.