Thank you Milan!
We do already use WP rocket too, combined with CloudFlare and the object-cache.php
It hasn’t caused any issues before and been running flawlessly like that for a very long time. So we are not sure why it is suddenly out of nothing causing issues now..
Thanks a lot for your reply and you offer to help out..
We have figured it out. It is the darn object-cache.php that is refusing to flush it’s cache for some reason. When disabled by renaming the file it suddenly works.
1. Do you use cache plugin with database/object cache, do you have some other cache layer on server for database?
ALL plugins disabled including cloudflare.
2. Most importantly, check your server php error log for errors.
There is ZERO entries about your plugin.
3. Have you tried to go back to older plugin version?
no change. It is stuck at this step.