Well, I was actually having the same problem. I tend to use the Ctrl+L shortcut to visualise what my players can or cannot see, so I was checking the Explorer mode this way. And yes, it was showing me everything, no matter how many times I hit the Reset Fog button. But when I hit Re-Join as a Player, and I select a token, it seems to work perfectly fine. The fog totally covers any non-explored area, and it darkens and "freezes" the explored ones, which is the way I believe it works, right? Just wanted to suggest trying it, because this is way more convenient than having a second test account, and it worked for me at least.