As a rental strategy for non owner occupants, it absolutely is a fantastic way to generate the highest return, that's true.....but also, and most importantly, your screening has to be on point, and without that, it won't be as effective because one bad roommate can ruin the environment for the other roommate tenants. 

You'll really need to screen your property manager/contractors.

Find out who has good Google Reviews (and responds to them), find out who answers their phone, find out who has a polished and professional website, etc. 

Next time please screen better or use a PM. 

Would love any leads to help me solve this problem even if it means making some phone calls.

Are you open to speaking via phone or zoom possibly.

you will still have to hit the phone, keyboard and pavement, but accuracy and reports are superior.   

We went to Delta Build's office on Monday, left our phone number and was told someone woukd get back to us within 2 days. 4 days have passed and no one has called us back.

Love it.Best advice I can tell you is to prospect prospect, you must lead generate, meet people tell them what you do, preferably face to face, but also on the phone, online etc, albeit I prefer and spent most of my time on face to face meeting and conversation.

.: I have similar result, only like 30 - 40% of data yield valid phone numbers.