I am also running into this issue. Additionally and possibly related, the ios run/debug configurations show a “no simulator device available” message. The “multi-os engine actions -> open project in xcode” context menu option works fine. Have tried uninstalling and re-installing the multi-os engine plugin, I’m at a loss as to how to proceed.
MacOS 10.12.6
Android Studio 2.3.3
XCode 8.3.3