I just now noticed this too myself a little bit ago… Well, I noticed it first about 2 to 3 weeks ago while in a hotel room while trying to watch a movie with a buddy of mine I work with and I just thought it was because of a slow Internet connection in our hotel room but just tonight I tried watching another movie with him in a different hotel with better wifi, from my iPad and had the same exact problem.
After doing a little bit of research, it sounds like it won’t do you any good to get with Apple on this because from what I gathered, due to the ongoing battle against piracy, there’s some new copyright or copyguard-type stuff going on with this new iOS update that makes it to where like if a specific streaming app doesn't want to allow screen sharing through that wired HDMI adapter, Apple had to honor it by incorporating something into the software that prevents mirroring what’s on your iPhone or iPad to your TV while using a particular app.
Some streaming apps don’t care but others do. Some of my streaming apps, I can screen-mirror just fine but some of my other ones, I can’t. They’ll play just fine from my phone or from my iPad but as soon as either device recognizes when the AV adapter is plugged in, all the sudden I start having terrible playback issues which consist of choppy picture with no audio, black screen with audio or a white screen that looks like it’s heavily pixelated, with audio.
Being that I spend a lot of time in hotels with my job, I’m probably just gonna have to invest in a cheap Google Chromecast so that I can cast whatever I want to watch from my phone to any TV, no cord necessary to make some paranoid corporate exec think I’m trying to steal copywrited material.