You put $50,000 down and mortgage $450,000 for a monthly payment of $3,000.

The problem with lender is they can't anticipate market risk volatility, almost as similar as subprime mortgage lender; lot of these lenders are just assuming "favourable market condition" would continue without end.

Do existing mortgages get wiped out?

It sounds like the idea is good for more of a SFR, or a 1-4 unit rehab but my concern from a lender's perspective is the needed experience in the more 10+ unit space to give "normal" (80% leverage) on a deal like this. 

I have been involved in a number of exchanges as an investor, a broker, and a lender. 

I have to prove who I am to my lender, not my agent. 

Notify your mortgage lender and insurance company of the transfer of ownership to update financing and insurance coverage.

95% occupied sorryPersonally I don't count the POH rent towards the NOI because my lenders won't either.30 occupied at $450 = $162,000 gross incomeAssuming a 40% expense ration your NOI would be $97,200If you wanted to buy at a 9 cap you'd be at $1,080,000Definitely check my math but I'd try to pay around $1 million for this.

I am a local loan officer that works for a mortgage brokerage in Chandler also, let me know if you have any other questions. 

Contractor was slow, so I started my own team Did you work with any real estate professionals (agents, lenders, etc.) that you'd recommend to others?