Composer package in registry created with API is empty and has size of 0 Bytes


i have a question regarding the gitlab API and publishing composer packages.

I use the API to create the package as mentioned in the gitlab docs.
Everything seems to work, i get a 201 status and the package gets created in the registry.

The only problem is the package has a size of 0 Bytes and is completely empty.

Can someone tell me what i did wrong? There is no error so i have absolutely no clue what went wrong and where to start debugging.