After accessing the supposed-to-be-hidden page, the is_hidden value is changed to 1
Here's a example
(Should not see)
id,title,comment_count,participant_count,post_number_index,created_at,user_id,first_post_id,last_posted_at,last_posted_user_id,last_post_id,last_post_number,is_locked,is_sticky,hidden_at,hidden_user_id,is_approved,slug,is_private,votes,hotness
422,foousertitle,0,1,2,2018-10-15,21:09:28,168,6575,2018-10-15,22:13:43,168,6576,2,0,0,2018-10-15,22:15:43,168,1,foousertitle,0,0,0
422,foousertitle,0,1,2,2018-10-15,21:09:28,168,6575,2018-10-15,22:13:43,168,6576,2,0,0,2018-10-15,22:15:43,168,1,foousertitle,1,0,0
Should be able to see
537,test,2,1,3,2019-01-16,21:45:30,1,8711,2019-01-16,22:19:38,1,8713,3,0,0,NULL,NULL,1,test,1,0,0.0000
Edit:
note: If I am a recipient of the discussion, my visiting doesn't trigger is_hidden and is still visible to anyone
Edit2:
I manually flagged my own private discussions and there's no more "buggy" ones.
New ones are created correctly.
Not sure why that happened