AWS Lambda JavaScript - Runtime.ImportModuleError: Error: Cannot find modul

We are getting an error with our lambda function(JS)
Runtime.ImportModuleError: Error: Cannot find module '@ourprivatemodule/src/service'

the module(@ourprivatemodule) is a private npm package
we checked the zip file uploaded by our bitbucket pipeline- and in the node_modules folder our module exists along with other modules like axios, @nestjs/core etc...

any stuff that we may have missed that may have caused this error?
its weird since other modules are 'found' and yet our particular module is not.. yet it is in the folder with the other modules