Repro steps:
1. Create a new timeline or select an existing one
2. Create a Track Group
3. Within the Track Group, add a track which has a game object reference (i.e. an activation track, audio track, or animation track)
4. Select the Track Group and duplicate it
5. Observe that the duplicated tracks no longer retain their game object references

Expected outcome:
- Tracks within duplicated Track Groups to retain their game object references

Note:
- Duplicating tracks outside of Track Groups seems to work fine.
- Doesn't seem like a regression, repros in 2021.2 up to 2022.1