Below you can see my simplified DB model:

Due to an error there are only null-values in the column Job.location where the entries belong to a certain Plan. Therefore I want to update all Jobs associated with this Plan, setting Job.location to Location.name of the User, who owns this Plan.
I tried this SQL query:
update dbo.Job set location =
(select name from dbo.Location as loc where
loc.objectid = objectid and loc.user_id in
(select userid from dbo.[Plan] as p where p.planid = 20))
where planid = 20
However, the result is always: 0 rows affected. The subqueries itself work correctly.
How can I achieve that all Jobs with a certain planid are affected?