The water department told them that they were seeing continuous usage—AKA a leak.

Housing costs and rents are through the roof while incomes have mostly remained stagnant.

Does it have material defects such as a roof, foundation, heating system issue etc?

I got a very good price on the building (about $25k per door), but it was a ton of work as in addition to tenant issues, there was TONS of physical distress (foundation repairs, sewer line and water line repairs, electrical upgrades, new roof, and apartment renovations needed for all units). 

Put a new commercial roof and did mold abatement and full demo of everything inside so i have ~80k into it.  

A roof, HVAC, and foundation on a $80k house cost the same as a roof on a 250k house (assuming a similar size but better location) with a similar PITI to rent spread.

Upper levels with slanted roof lines cut into living space which is very outdated and much of it becomes deadspace. 

Despite the competitive pricing and the fact that it’s been completely remodeled (new roof, HVAC units, windows, floors, appliances—you name it), it’s still sitting on the market.I’m trying to figure out how to get this property to sell faster while still turning a profit.

I've got the common sense items such as clean the lint trap, report leaks ect.

To them a 5 year old roof is in good shape for the near future the same as a 18 year old roof.