FWIW, today, when Step Counter is active, everyone is getting the console log popping up at the start of their turn, with this error message:
Attachment 67939
I, as DM, am getting that error at the start of every actor's turn, whether Step Counter is active (i.e., the button is clicked) or not.
I exited the game, removed Step Counter as an extension, and restarted; no more error message.
Also, while Step Counter was active, the round counter was not automatically incrementing, even if I clicked the Next Round button. Once I restarted the campaign without Step Counter active, the round counter incremented.
Finally, there were a couple of points while Step Counter was loaded and active where moving 5 feet used up a hundred or two hundred-odd feet of movement. No idea what that was about, but I bet it's probably the same root cause.