Have reviewed your install and am a bit stumped. I can't see any reason for this nor can I replicate the issue in tests. The query also looks fine, which is as follows.
Code:
SELECT COUNT(*)
FROM `#__users` u
INNER JOIN `#__comprofiler` AS ue
ON ue.`id` = u.`id`
WHERE u.`block` = 0
AND ue.`approved` = 1
AND ue.`confirmed` = 1
AND ue.`banned` = 0
AND ( SELECT COUNT(*) FROM `#__user_usergroup_map` AS g WHERE g.`user_id` = ue.`id` AND g.`group_id` = 2 ) > 0
AND (JSON_SEARCH( LOWER( ue.`cb_offered_job` ), 'one', 'on board', NULL, '$**.cb_onboard_or_not_company_offer' ) IS NOT NULL)
AND ( (ue.cb_offered_job != '') )
I created a new field group field and it worked perfectly fine. Then 10 minutes later started throwing the same error. I'm not sure what's causing this, but seams to be something server related. Maybe an issue with MySQL configuration? You're on the right version to be able to use the JSON functions so am not sure why it's erroring.
Please try contacting your host and see if they can review the MySQL error log if enabled. If not enabled see if they can enable it then retrigger the error and check the logs.
Do you have any server side caching configured? That could also be a possible culprit. Looks like you're using cloudflare so that's a very likely possibility that caching is causing problems here. Typically you don't want to cache any form requests.
krileon
