I would verify that the huge ventilator is working as it was suppose to. Also that you are changing filters to filter off any oxidized cruddies that might smell worst over time in your machine?

Is someone changing the drive belts on the extractor fan and are any filters plugged up ? Has anyone changed the construction of any make up air inlet points?
Has any old maintenance staff retired and not told the next guy what the job entials to keep your vent working?

Are any of you tanks or dryers running hotter than they are meant to? That could push up the evaporation rate.
I had a thermocouple in a pre developer wash bath die, and the heater in that bath consequently took off an pushed the bath to 50C. The increase in humidity cued me to that.