Home Office Deduction??

[Lauren Keen Aumond]

I'm using a CPA for the first time since 2017 was my first year having a rental property. He's my parents' CPA and they have one rental. He told me I can't take any home office deduction (I'm interested in the "simplified one" $5/sf) because I'm not a Real Estate Professional (750 hours spent or half my regular business time). In Amanda and Matt's book, Tax Strategies for the Savvy Real Estate Investor, they say if your home office is "your primary place of business" for real estate activities, then you can deduct it. This is definitely true for me, however, I can't find if Amanda and Matt mention the Real Estate Professional definition as a requirement for that or not.

If I can take the deduction, can you send me some collateral I can forward to my CPA? 

(And I already know I need to find a different CPA because I came with more ideas than he did. This is a DIFFERENT discussion.)