Just to report this bug in SMF 2.1 beta 3:
Looks like guests count at the top of each topic doesn't work properly. I visited the topic with chrome incognito mode(not logged in), it shows 1. But at the same time I checked the same topic with my Admin account and it shows 0 guests.
Was caching turned on?
Not necessarily a bug, there are times and ways this is completely legitimate behaviour.
No, the caching is off.
Sure? It's on by default.
Do you mean this one?
(https://ctrlv.cz/shots/2017/08/07/dNPP.png)