"Not correctly licensed" error
If you try to drive a train and get a grey error box on the screen with white text telling you that the train is not correctly licensed, the solution is to install the newest version of the train. This error was generated during the update from TS2018 to TS2019 and has since been corrected in all the newest installation files.
Make sure you look at which train is giving the error message - the error box will tell you. For example you could be driving the IRM in a scenario but another train in that scenario might be giving the error.