@Carl what do you think?
Depending on the time frame, how could they fly out to Hawaii? With the airlines practically grounded, it's perfectly possible that one could not have flown no matter how much money they threw at the airlines. It most certainly would not be feasible to fly there and be forced to quaratine for 2 weeks just to deal with 1 or 2 days of "arrangements" for a rental property.
As far as proving anything, it's only necessary if the IRS audits you on that specific item and asks you to prove it. Realistically, I just don't see that happening to small time landlords like you and I. Unless of course, you give the IRS something that would raise an eyebrow, thus giving them reason to look at your tax return with more scrutiny.
Technically the house was on the market for the whole year,
Actually, there's really nothing "technical" about it. Either is was on the market, or it was not.
But if you decide otherwise, that means you converted it to personal use on your 2019 tax return thus stooping depreciation on all rental assets, and then you converted it back to a rental on some date in 2020. Doing that involves a lot of manual math on your part - as the program just can't handle it automatically and do so correctly.
