During the elastic analysis you get the error:
WARNING: Global buckling factor < 1 at « Selfweight »

[NL]: WARNING: Globale knikfactor < 1 bij « Selfweight »
[FR]: WARNING: Coefficient de flambement global < 1 chez « Selfweight »
[ES]: WARNING: Factor de pandeo global < 1 en « Selfweight »
Solution
More information in this article.