vb.org Archive - Channels not marking as read?

There is a very peculiar issue that's been affecting our forums for quite some time now. For some users, the Mark Channels Read button isn't marking any channels as Read, and some of the Channels appear as Unread spontaneously, even if no new posts have been been made.

We tried changing a few things ourselves, and it seemed to take care of this problem, but it just started happening again. Here's the list of what we already tried:

Changed Marking type to Cookie based. I changed to cookies,and then back.
Changed Marking type to Database (no automatic forum marking)
Changed Marking type to Database (automatic forum marking)
Launched forum Maintenance
Cleared system cache
Updated to the latest version of vBulletin
Changed Cached Post Lifetime from 7 to 10 days

I'd really appreciate if you guys could help me out with this one. It's very annoying.

Thank you!

X vBulletin 3.8.12 by vBS Debug Information
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Messages:

X vBulletin 3.8.12 by vBS Debug Information

Page Generation 0.00863 seconds
Memory Usage 1,699KB
Queries Executed 10 (?)

More Information

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Hooks Called:

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Messages:

X vBulletin 3.8.12 by vBS Debug Information
Page Generation 0.00863 seconds Memory Usage 1,699KB Queries Executed 10 (?)
More Information
Template Usage: (1)ad_footer_end (1)ad_footer_start (1)ad_header_end (1)ad_header_logo (1)ad_navbar_below (1)footer (1)gobutton (1)header (1)headinclude (6)option (1)post_thanks_navbar_search (1)printthread (1)printthreadbit (1)spacer_close (1)spacer_open Phrase Groups Available: global postbit showthread	Included Files: ./printthread.php ./global.php ./includes/init.php ./includes/class_core.php ./includes/config.php ./includes/functions.php ./includes/class_hook.php ./includes/modsystem_functions.php ./includes/class_bbcode_alt.php ./includes/class_bbcode.php ./includes/functions_bigthree.php Hooks Called: init_startup init_startup_session_setup_start init_startup_session_setup_complete cache_permissions fetch_threadinfo_query fetch_threadinfo fetch_foruminfo style_fetch cache_templates global_start parse_templates global_setup_complete printthread_start bbcode_fetch_tags bbcode_create bbcode_parse_start bbcode_parse_complete_precache bbcode_parse_complete printthread_post printthread_complete
Messages: