Screen turns black while using screen mirroring

Up till last week I streamed hbo weekly on macbook air via apple tv 3rd generation on my tv without any problem.

Today I wanted to watch a movie but I got a black screen with sound only. This happened as soon as I turned on the screen mirroring. I have updated all devices and also apple tv itself. Internet is fast enough.

I log in to hbo through web browser, so I do not use an app. I have tried safari, firefox and chrome. Also cleared caches. Contacted hbo and they informed me that they do not block any streaming. Have the same issue with netflix. But when I watch youtube vids, all works fine. Not sure what to do anymore. Anyone has the same issue?

Thanks in advance.