Unprocessable entity from API when assigning products

[Migweld]

The API call when searching for a variant in the related products form returns a 422 Unprocessable entity error. Expecting a list of matching variants.

AJAX exception is:

"exception":"Mysql2::Error: Column 'id' in field list is ambiguous: SELECT COUNT(DISTINCT count_column) FROM (SELECT  id AS count_column FROM `spree_variants` LEFT OUTER JOIN `spree_products` ON `spree_products`.`id` = `spree_variants`.`product_id` AND `spree_products`.`deleted_at` IS NULL WHERE `spree_variants`.`deleted_at` IS NULL AND ((`spree_products`.`name` LIKE '%Goo%' OR `spree_variants`.`sku` LIKE '%Goo%')) LIMIT 25 OFFSET 0) subquery_for_count"}

Gist of Gemfile.lock:
https://gist.github.com/Migweld/039aecad059d68278bd7

Any help appreciated.