A composition includes (A) 30-95 wt % of a random or homogeneous propylene-based interpolymer having: (i) a comonomer content of at least one of C2 and C4-10 α-olefins of 7 wt % to 49 wt % based on the total weight of the propylene-based interpolymer, (ii) a density of 0.90 g/cc or less, and (iii) an MFR of 1 g/10 min or greater (230° C./2.16 kg); and (B) 5-70 wt % of a block composite nucleator comprising: (1) a first polymer that includes polypropylene; (2) a second polymer that includes an alpha-olefin based polymer, the alpha-olefin being selected from at least one of a C2 and C4-10 α-olefins, and (3) a block copolymer having a first segment and a second segment, the first segment of the block copolymer having the same composition as the first polymer in the block composite nucleator and the second segment of the block copolymer having the same composition as the second polymer of the block composite nucleator.