Is the kbin/mbin a known issue by chance? I would assume that going by user ID would work no matter the originating location, but maybe posts load differently than saved profiles.

I'm going to see if there is another user from the same instance that I can use to see if it is instance related. Thank you for the possible cause to look into.

Edit: so after further testing if the user comments on lemmy.world it is hidden, but their comments from other instances (checked their comments on dbzero and .ml when blocked/not blocked) show up. Blocks of other users appear to be successful across instances, so it looks like it could be the kbin/mbin federation. At least the block partially works!

yay, database inconsistencies.

looks like kbin.earth has a broken setup at some point where their user profiles were using http instead of https urls and that results in random breakage in lemmy:

I can see all of their comment on the post, there are at least four or five. I wasn't paying attention to whether those specific comments were in their profile though.

Check five or six comments, only the lemmy.world ones were blocked correctly.

Yeah, I know. This was a case of a single user who was blocked, but showing posts external to lemmy.world (my instance) but successfully blocking on the home instance. MrKaplan looked into it and there was a sync issue with their instance and the user had duplicate records at lemmy.world so I had to block both.