Repro steps:

1. Create a page with a link to an anchor to another page in the same space.
2. Copy the page created in step #1. Specify a location in a different space.
3. Check anchor link (no longer works).

The problem is that no space information is included in the anchor link to an anchor in a page in the same space. When the home space of the page changes, the link no longer points to the right destination page. This happens even when you specify the space key in the link.

If instead of copying and changing the location you move the page to another space, the anchor works as expected.