Korean firm KTB Asset Management claims RFR Holding’s principals, Aby Rosen and Michael Fuchs, defaulted on payments related to a $205 million mezzanine debt for 285 Madison Avenue. Allegations, filed in New York Supreme Court, state they owe $1.5 million. RFR Holding borrowed $475 million in 2017, including loans arranged by KTB. The complaint seeks recovery of unpaid guaranty amounts. The property, an office building in Grand Central, spans 407,127 square feet and was sold for $189.2 million in 2012. It generated $29 million in revenue, or $71 per square foot, according to recent figures.