Mold needs moisture to grow.Look in the lease for inhabitable conditions clause to see if you can terminate the lease based on that. 

The unit has also been tested for environmental issues and moisture was below "dry levels" and indoor air quality levels were okay though CO2 levels were just above guidelines in some rooms.The tenant is known to use a lot of candles, we're wondering if this could cause this.Does anyone have any ideas?

I agree with Greg 100% on this one - and he's really being pretty gentle with you. 

Many landlords don't do what is necessary to mitigate the risk of mold and moisture in the home.

Basically I am wondering if anyone has ever had something happen to a property that created an issue for the tenant to stay there until repairs were made. The unit is roughly 500 sq ft and has two adults & a ...

Do some reading on basic HVAC design and you will learn that a larger system doesnt work better due to the fact that is does not run long enough to adequately cool the air and remove the moisture that makes you feel hot.

Or, get one of those zip ties that has the screw loop in the head, put the zip tie around the drain hose (gently), and run a screw through the loop into the cabinet. 

Materials: tub and surround, toilet, sink, vanity, mirror, vanity light, mold resistant drywall, GFI outlet, light/fan combo, flooring, paint.I installed 'luxury vinyl plank' flooring since the bathroom is a high moisture area, which was super easy to install and is holding up well.

By day I'm a moisture nerd specializing in concrete slab moisture testing for regional and national developers, homeowners, GC's, hospitals and retailers.Looking to take massive action in developing my real estate portfolio through a Buy and Hold strategy.

Easier to deal with now before fixtures go in than later when your floor sags from trapped moisture.