Bumping this thread to provide an alternative solution in case you get the "contains lists" error and don't want to rebuild the shortcut or delete all data.
In a recent scenario I had a relationship and a shortcut set up that would throw this error when viewing certain items in a form, or even displaying them in a query.
What I did, and what you could do is running this SQL query to look for duplicates in the BO reference table:
SELECT RID, COUNT(*) AS Count
FROM cars_ref
GROUP BY RID
HAVING COUNT(*) > 1;
If you do get results like...:
RID Count
4567 2
...then you need to delete the duplicate(s) so that only one record can have the same RID.
SELECT * FROM cars_ref WHERE RID=4567;
Delete one of the rows and the error will disappear.
Note: In my case, the reason for this error was 100% my own fault for tampering with the SQL tables by restoring some old data via SQL. This is why some duplicates were restored by mistake.
