Feed blocks, caching, and permissions

[Morgin]

Currently on 4.4 with upgrade planned for next week, so forgive me if this issue is resolved already.

I have a section of my forums that requires a minimum content count to see or access (the "off-topic" section). 

Every few months, I'll get a member who will randomly start a topic in our support area asking how they get access to these "hidden" topics. Usually some variation of "I see a bunch of topics in the "Recent Updates" block that I can't access and get error code 2S136/V. How do I access them?". 

I've checked every time to see if somehow "honor permissions" on the block setting got turned off, and it's always fine. The user can't see the topics (or even the forum itself). Settings on the forums are:

•       Minimum content count to see forum: 10 approved items of content (posts, comments, etc.) 
•       Users without read permission can open forum? (UNCHECKED)

I'm assuming this is perhaps some sort of caching issue? Strangely, if I login as that user, I can't ever see these topics in the sidebar block. Apparently they don't consistently see them either - they just pop into the block from time to time.

Is there any possibility the block caching is somehow bypassing the permissions system? Alternatively, is there some possibility that because the user is a member of a group that CAN access once the requisite content has been contributed, the block permissions is ignoring that and focusing on whether the member group as a whole has permission?

I also use cloudflare, but it doesn't cache any dynamic content so shouldn't be interfering with my block permissions.

At a bit of a loss on what's going on. Any advice appreciated!