Yes, I'm not sure what the limit it, but it has been stated by other that there is a daily limit to loot and xp gained from Foundry missions. It also seems to reset at the same time as Dilithium refinement.
I think the drop cap is based on recycled loot - perhaps in EC terms - as soon as you have recycled around 500k it stops - some people who are not recycling in mission and letting it build up in their inventory might be getting more. As most people don't go in there with 50 open slots+ they end up recycling a lot and soon the drops stop.
There should just be an Energy Credit crate that takes up most of the loot table. That's all we're doing - selling the stuff on as soon as it comes in. Maybe that way equipment would increase in value.