Cannot Create Tables of Contents for imported pages from a different wiki

When the user import a page from a different wiki that is not from Atlassian and then include a table of contents , all the links point back to the old wiki. If I create a new table of contents all of the links seem to point to the top of the page rather than the header that they should.
We tested and removed the headers that are not working and added new headers and it seems to work but if we added more headers without removing the old headers the problem persists. It seems a malfunction in TOC if we import from a different Wiki.