eBOM is not updated when saving a Solidworks drawing, it is only updated when saving the 3D Data or assembly.
It would be a nice a addition if the Solidworks plugin had an option that could be activated/deactivated to also update the eBOM when saving drawings.
For example, when saving a drawing you could receive a message.
"eBOM doesn't match cBOM, do you want to update it?" Yes or No