I haven’t experienced this, but here’s something that could help with tracking down the bug.
Next time it happens you can hit F12 to bring up Developer Tools and go to the Console tab (This works for most browsers, but Safari is a bit different[1]). With the Console open, try clicking it again. If there are errors popping up, you can post a screenshot to help give more clues as to what’s going on.
For Safari: Go to Safari’s Preferences (Safari > Preferences in the menu).
Click on the Advanced tab.
Check the box at the bottom that says “Show Develop menu in menu bar”.
Press command+option+c to open the Console. ↩︎