Amenability of Thompson group is a longstanding open problem ...here is a paper by Uffe Haagerup 2015 on this.."A computational approach to the Thompson group F" https://arxiv.org/pdf/1409.1486.pdf
NON-INNER AMENABILITY OF THE THOMPSON GROUPS T AND V UFFE HAAGERUP AND KRISTIAN KNUDSEN OLESEN 2016 "In this paper we prove that the Thompson groups T and V are not inner amenable. In particular, their group von Neumann algebras do not have property Γ. Moreover, we prove that if the reduced group C ∗ -algebra of T is simple, then the Thompson group F is nonamenable. Furthermore, we give a few new equivalent characterizations of amenability of F"
https://arxiv.org/pdf/1609.05086.pdf