What happened

In attempting to set up a system to transport minecarts automatically between stacked dimensions, I discovered that chest minecarts eject their inventory when crossing the dimension border. Donkeys and mules, however, do not lose their inventories. Chunk loading on either side of the border does not seem to make a difference.

While the idea of employing donkeys in minecarts to transport items is amusing, there is no vanilla means of injecting items automatically into equestrian inventories

Used versions

Minecraft-1.12.2
VerticallyStackedDimensions-1.12.2-0.1.9
CD4017BE_lib-1.12.2-6.5.1
Forge-14.23.5.2854

The dimensions involved in the stack are the Overworld and "The Beneath." I have not tested other stack arrangements, but I have no reason to believe that the inconsistency is isolated to these two. I utilized the "world spike" chunk-loader from "Railcraft" to test whether or not chunk loading contributed to the problem.