Hi,
The default value in xTensor is True. If you only load xTensor and evaluate this variable, you'll get True. But you are also loading xTras in this notebook. xTras loads Invar, and Invar changes the default value of this variable. Note the last message line when loading Invar:
** Variable $CommuteCovDsOnScalars changed from True to False
Cheers,
Jose.