Why the check for fatigue or brittle failure is not performed?
The necessity for a brittle failure check is to work under EN 1992-2 code and to check the checkbox in the Data tab (BIM, Beam, …) or Calculation control (RCS). Moreover, the brittle failure check is done for quasi-permanent combination, therefore there must be one defined in extreme.
Fatigue check requires having it switched on already in Project data (mainly in RCS) or set appropriate national annex (for instance NN). Another requirement is to set relevant load cases as fatigue types. This load case will be included in the combination, which evaluation needs to be set as ULS Fatigue. After this setup, the check of fatigue should be performed correctly.