I'm looking to use it as an investment, not a primary residence.

My primary focus is on the BRRR method, with a greater emphasis on appreciation over cash flow.For those with experience investing in Cleveland, I’d greatly appreciate any insights on neighborhoods worth focusing on.

I currently own a 1 bed 1 bath single-family house as my primary residence.

However, to my understanding, a 1031 conversion of an investment property to your primary residence after a safe harbor of two years does not trigger a tax event.

@Kris TohovitisI wouldn't recommend using your cash to pay off the mortgage on your primary residence since you can likely get a better return on that money by investing it.What's your buying criteria for the multi-family property?

From tax stand point I would think you can separate from primary and be okay with IRS being that IRS will not be local code enforcement.  

I strongly advise you to get your primary residence taken care of FIRST.

In some cases, after running the numbers, I’ve even faced potential negative returns, causing me to miss out on promising deals here in South Florida.That brings me to my question: I currently own two homes—one is my primary residence, and the other is a rental property.

Since there is a co-owner, you would have to purchase the property and it is really hard (if not impossible) to pull a HELOC as the basis for the purchase (since it is not your primary residence). 

If you can get a better primary residential HELOC rate than you can a hard money bridge loan I would say yes.