I currently have Adobe InDesign version 15.0.1 x64 and when I log in it tells me that I have missing plugin's (see below for a list). I am still able to do all other functions but then when I go to package my document it is unsuccessful. The research I have done says I need to add these plugin's but I can't find where to do that in the Help section. I have even uninstalled the app and reinstalled it and I'm still experiencing this issue.
Bastian S. commented
Not a fix but a workaround: Create a IDML and then try to package it (Make sure to check for changes after the IDML Process) if you just need to gather all the links you can use the Adobe Bridge for that - Right click the indesign file - there should be an entry to show all linked filed somewhere in the context menu - then simply compy and paste them to your Links folder.
Hope someone can help you :)