Entity query done by entity lookup plugin fails to return entity which generated SQL query returns

Problem/Motivation

I'm having problem with my migration where I'm trying to match existing user profiles (created with profile module) with new data imported from CSV file. profile_id mapping fails, even though underlying SQL query return the correct profile ID.

The important part of migration mayors_profiles looks like this:

  uid:
    plugin: migration_lookup
    no_stub: true
    # previous user migration
    migration: mayors_users
    # property in the source data
    source: lau
  dump_uid:
    plugin: callback
    callable: var_dump
    source: '@uid'
  profile_id:
    plugin: entity_lookup
    entity_type: profile
    bundle: profile
    bundle_key: type
    value_key: uid
    source: '@uid'

Steps to reproduce

• add and install modules profile, migrate_plus, migrate_source_csv
• create a user, use the mail from primary_mail field of the source data
• create a profile type profile, add some field to it (like field_first_name)
• create a profile for the user you've created
• create a module to store migrations and the source data (please remove .txt extension).
• clear the cache
• run mayors_users and mayors_profiles migrations. Please adjust the path to the source data.

By running query like:

SELECT ufd.uid, ufd.name, pf.profile_id from users_field_data ufd
LEFT JOIN profile pf on ufd.uid = pf.uid

you'll see that second profile has been created. The reason is that $results is empty at https://git.drupalcode.org/project/migrate_plus/blob/HEAD/src/Plugin/mig.... However, when I enabled query logging in MySQL DB, I see that this SQL query has been performed by the entity lookup plugin:

SELECT base_table.revision_id AS revision_id, base_table.profile_id AS profile_id, profile_2.is_default AS is_default
FROM profile base_table
         INNER JOIN profile profile ON profile.profile_id = base_table.profile_id
         LEFT JOIN profile profile_2 ON profile_2.profile_id = base_table.profile_id
WHERE (profile.uid = '153')
  AND (profile.type = 'profile')
  AND (profile.status = '1')
ORDER BY profile_2.is_default DESC, base_table.profile_id DESC
LIMIT 1 OFFSET 0

When you replace the profile.uid in the WHERE clause by the uid of the user you've created, you should get a correct result.

Why this issue happens?

Proposed resolution

The entity lookup plugin should return the profile_id of the profile user already has.