A recent influential article by Liu, Liu, and Xu gave a new example of a 42-dimensional (singular) irreducible symplectic variety with a Lagrangian fibration. This is obtained by compactifying a construction by Iliev and Manivel arising from cubic fourfolds and fivefolds, together with techniques developed recently by Saccà. In work in progress with O’Grady and Saccà, we consider the case of Gushel-Mukai manifolds, by obtaining an example in dimension 20. The approach is similar to Liu-Liu-Xu: we compactify another construction by Iliev-Manivel, but with technical complications due to the Gushel-Mukai setting.