Solved! Open apps button behaving as home button

May 31, 2019
Was looking through developer settings on Android 8.1.0, don't know what I did, but now the open/currently running apps button takes me to the home screen. Also, holding the home button no longer brings up google assistant; and the running apps button vibrates twice, once when I press and once when I release, the home button only vibrates once. Any ideas?
Sounds like you need to get yourself back out of developer settings. Taking the phone back to normal usage. When the phone restarts, it should resolve the issue.