In DTPO, I have an RTFD document and I put item links into it via ‘copy item link’. Later, when I click onto this link, that document appears in the preview window - no matter where in the DB this linked document lives. As expected.
Once synced to DTTG 2.0.6, item links only seem to work when they point to documents in the same group at the same level. If the linked document is in a sub-group, or in any other group in the DB, an empty screen only displays “nothing selected”.
I haven’t used this mechanism since the DTTG 1 days, but I am quite certain the item links worked properly and globally back then.