Unsure if this is a modded cart issue or not, but this is the second time in several hours the carts have disconnected. The train was Loco : Tank Cart : Diamond : Iron. It disconnected between tank and Diamond cart.

http://i.imgur.com/4PYl9Le.jpg

Edit:
RC version 9.12.2.0
Forge: 10.13.4.1566

Duplicate of #882

#882 references 1.10.2 and game restarts, this is not in the same version nor dealing with game restarts, is it still the same issue?

Edit, I am on 1.7.10

I think this bug actually presents on both versions, but is more observable on Minecraft 1.10.2.

Oh, I didn't notice that...hmm...