Ag sciences that where loaded into rocket disappeared in transit to platform. Lost several hundred before I figured it out. If they where loaded by any other way than robots with the automated requests from orbit around 800 would be lost. Not lost due to spoilage just gone.
With or without MODS only robot load would not cause a loss.
I assume you are using CircuitLaunchableRockets mod.
At first I thought it could be caused by some mods conflict, but no. I was able to reproduce it with vanillaSA+mod (v1.1.6) only.
It seems that there is some mistake in its rocket_launch_ordered function. It receives a cargo pod containing 899 items, and creates a new cargo pod containing only 200.