I've tried to scale down a single fruiting medium to 100-200g, and it keeps failing time after time: at best, I get small needle-sized fruiting bodies (hypsizygus tessulatus, post picture) or primordia and then small malformed underdeveloped fruiting bodies (pleurotus eryngii, inline picture). Then development just stops. Medium is enriched (sugar) alder chips, contamination starts developing long after growth is stalled. Is it really scale problem? What's the reasonably smallest batch size?
I've never grown those mushrooms, and different species have different needs.
My question to you is what was your set up for the "scaled up" conditions? What are the differences? Did you top fruit in a massive jar? Or use some other container? Did you control humidity differently?
It's usually an issue of air flow or humidity assuming you have a healthy culture with the right nutrients.