Web Inspector's 'All Resources' not showing anything!

I’ve just really noticed this in the last few weeks, but now I realise something’s actually wrong with Web Inspector. On any website, particularly one that’s very image orientated, and I do ‘Show Page Resources’ e.g. to list all the images/graphics the website uses (very handy if ‘Save Image As’ is disabled) instead of it showing the list of all the images I’m instead getting a blank page, with the only thing showing being a greyed out ‘No Filter Results’ button. Why would this be happening when a month or so ago everything was fine? All the other tabs (Debugger, Timelines, Storage, Console, Elements, Network) show their respective information as normal.