Steps to Reproduce:
1. Start up Liferay DXP SP6 + FP39
2 .Deploy Liferay Audience Targeting 2.0.0
3. Restart DXP
4. Navigate to Configuration > Audience Targeting in site administration
5. Add a user segment with any rule
6. Uninstall Liferay Audience Targeting 2.0.0
7. Deploy Liferay Audience Targeting 2.1.2
8. Restart DXP
9. Log in
10. Navigate to Configuration > Audience Targeting
11. Add a campaign, click Select button under User Segments.
The user segments that are created with 2.0.0 should be listed and can be selected.
The user segments that are created with 2.0.0 are not listed in the User Segment list when creating Campaign.