Its not an Accureather problem it is a Forecastfox problem and its been around for months / dare I say year(s). I use an animated Wunderground radar image and the only way I can get it to refresh is to close and reopen FF, it is the same with the animated Accuweather radar image as well.
As far back as I can remember this has been an issue for animated radar images, in fairness I should mention I came from forecast bar enhanced where updating worked flawlessly. Since the switch the radar has been hit or miss on updates.