Sure, it simply looks darker just like right after the click:
So what happens when the page refreshes or automatically logs out after some time, it takes some time for button to become "clickable" and turn from darker to normal. After you click it, it turns darker again. The thing is that you can never click it twice. So the potential issues might be caused by local connectivity or machine loading page slower? or maybe the UI slightly lagging behind, sometimes I need to wait 2-3 seconds for things to happen, sometimes I need to refresh my page and try again, then it usually loads quickly.
Personally I operate on a slow connection in my current location so the effects of slower loading times and, sending data and perhaps UI lagging/bugging are exaggerated by poor connection. I could probably run some debugging on browser and measure loading times if that's going to be helpful.