Every once in a while a tab will not close when I click the X. I am able to switch between tabs and use everything else like normal when this issue is happening. The X will still highlight, I am able to close other tabs just not a specific one. Literally the only thing that will not work is actually clicking the X and having the tab actually close. To close it I will have to drag it to make it its own window and then it will allow me to click the X.

I have not noticed a pattern to what tabs randomly decide to do this or the frequency to how often it happens.