Thanks for the bug report.
Can you please elaborate more on the following:
he ACF v4 to v5 migration process is working, it’s treating those imported but not ordinarily visible fields as actual fields, and migrating them
I don’t really understand what you mean about the ‘hidden’ fields.
Looking forward to fixing this issue,
Welcome to the Advanced Custom Fields community forum.
Browse through ideas, snippets of code, questions and answers between fellow ACF users