Unfortunately, you’ve misunderstood the nuanced meaning that the phrase “en masse” has acquired in the English language:
Cambridge Dictionary: En Masse
However, you can take comfort in knowing that you are not alone in this misunderstanding:
No I understand what en masse means. I just don’t subscribe to your inflexible interpretation.
Language is a tool for communication. It’s for the masses, not something to be gate kept or preserved by the priests of lingual orthodoxy. If the words you use convey the intended meaning to the listener, then the wording is adequate.
If everyone’s use of language was as rigid as the people insisting we can only use the phrases as they existed when they were imported to an English court by a Norman conqueror a thousand years ago, then we’d all still be communicating by banging rocks together and grunting. The English language evolves every day. It’s alive.
