joining 2 tables - resul different as desired

joining 2 tables - resul different as desired

So here I am again. I have 2 tables:
ci_products:

ci_prodimages:

I have SQL query with join and GROUP_CONCAT.
SELECT *, GROUP_CONCAT(img_url) urls FROM (`ci_products`)
JOIN `ci_prodimages` ON `ci_prodimages`.`img_pid`=`ci_products`.`prod_id`
WHERE `prod_cat` = '4' OR `prod_cat` = '8' OR `prod_cat` = '9' OR
`prod_cat` = '10'
This SQL should return all 3 products. But it only returns the one with
prod_cat - 10. Everything else is working but this.
Also this query:
SELECT *, GROUP_CONCAT(img_url) urls FROM (`ci_products`)
JOIN `ci_prodimages` ON `ci_prodimages`.`img_pid`=`ci_products`.`prod_id`
WHERE `prod_cat` = '9'
Results in null result.
Any help appriciated. Thanks