Hmmm, are there any consistent ways to reproduce the issue, or is it seemingly just a randomly-occurring thing?
Halfway randomly occuring, it seems to happen half of the time when I attempt to run over 1 unknown tile and release right before moving on the said tile. I usually try to have at least 1 known tile in between me and the tile I want to run over because otherwise, I find I'll usually run 2 unknown tiles even after I had released the first.
In other words, I'm basically complaining about a responsiveness issue.