Scrap separation plant never reaches 100% production percentage

[Los]

I got a big dump with claw machine and rail full of mixed waste and factory connected to my scrap separation plant and have it nearly always fully staffed but the production percentage never seem to go above 50% and both outputs (the scrap metal to aggregate storage and a factory connection to my general separation plant) and both outputs are not full but cant seem to be able to get production high enough (i'm importing mixed waste which seem to have 10%> metal scrap in it if that's relevant)
Power also seems to be not an issue and the green text "Operating without issues" is visible

[Spencer]

Workers substantially loose productivity if there is no drinking water or overfilled sewage tanks. Same goes for full waste containers of the building. Maybe any of these are the problem? Or in general your loyality (for 100% productivity the loyality must be 60% or greater)

[High King Lemur]

Originally posted by Los:

the green text "Operating without issues" is visible

That means the factory doesn't have any productivity issues. Check worker productivity as well - hover over some worker icons in the separation plant, there should be a productivity stat for each worker.