When I plug in my HDMI cable and want mirror screens to watch a movie on my TV I just get a picture of my background and in the bottom left corner comes a cog and in the bottom right side there are a lot of dots in a square but no more if I go over to HBO on the phone and start a movie then only the sound comes on the television but no movie only the same pictures that have always been when I start mirror screens
what to do?
why new cable? the one i have is also usb-c i can use dex on the computer screen so i can write on the computer, so i should also be able to see screen mirror with this cable?
i fix it by a totel reset to factry
I had a similar issue and found a fix. In my case I had enabled developer options in settings and had turned on Force Desktop Mode. Once I turned it off again the HDMI mirroring worked as normal when I turned off Dex.
See the picture below for how it should look: