After Beta 57b5 update on my desktop the Theater Mode is not working correctly on YouTube, it's just creating the black bars on the side but not increasing the size of the video as it did before and how Chrome behaves. The weird is that on my laptop still working correctly. My Desktop resolution screen is 3440x1440 and my laptop 3200x1800. Using Windows 10 Pro on both devices. Already reset my Firefox and tried Safe mode, none of them worked.