Maximal green sequences are studied in many papers. For example, Maximal Green Sequences for Cluster Algebras Associated to the n-Torus by Eric Bucher, On Maximal Green Sequences by Thomas Brüstle, Grégoire Dupont, Matthieu Pérotin, Minimal length maximal green sequences by Alexander Garver, Thomas McConville, Khrystyna Serhiyenko, Maximal green sequences for quivers of finite mutation type by Matthew R. Mills, Maximal Green Sequences of Exceptional Finite Mutation Type Quivers by Ahmet I. Seven.

Which cluster algebras where the existence of maximal green sequences is still unknown?

Thank you very much.