as Andrey Osadchuk already said: if you are still within the same organization (organization ID), you just need to change the report suite (in workspace projects) or access the desired elements (segments/calculated metrics). there is no need for any migration since especially segments/calc. metrics are independent of the single report suite.
there might be additional problems why users can't see the desired items:
1) report suite settings: using another report suite with different settings might cause problems
2) permission management: users don't have access to the right items
3) virtual report suite: access to items has been restricted on a virtual report suite.
according to your description I would check for permissions to solve the access problem.