My wife and I self manage a mix of short, mid, and long term rentals.

If you can't get ahold of the PM, demand letter is next.

Letters are a good start.

I'm finishing up the last of my engagement letters for next year and I know many of us will have sporadic availability for tax planning after this week due to the holidays. 

If the complaint is legit, the offender will be cited and you can use that as evidence for a violation letter, termination, or eviction.Second, if the offense is real, I recommend starting with a written warning.

I'm guessing you got the same letter I received from REVA, although mine was in reference to a different DST - Reva One. 

As to asking the IRS reps, let me limit my comment to just three letters: LOL

I plan to continue to invest in a mix of both RE syndication and our own rental properties going forward depending on what makes the most sense and offers the best returns. 

Check county recordsUse online search tools like PropStream, Reonomy, PropertyShark, etc.Use local GIS mapping tools (ask your county)Search online directories for LLC or TrustTalk to neighborsHire a skip tracerSend a letter to the propertyThere are a lot of options.

The other two have a mix of ideas.