Because it is a triplex and is only using about 1/3 of the cost, it MIGHT be able to be fixed with Form 3115.  The new tax preparer could say that the depreciation taken was for the ONE unit, and that the SECOND unit was NOT depreciated at all (which DOES qualify for 3115).  So if the numbers match up for that, that would definitely have the best result.  Has the 2018 tax return been filed yet?