Android Studio 2.1.1: "no usb devices or running emulators detected"
<p>Suddenly my Android Studio stopped detecting all my devices, none of them is working. It happen from one execution to another. I've changed a few lines of code (1 min maybe?), hit run (instant run) and then I missed all my devices.</p>

<p>I'm using a Mac and as devices: Nexus 5x, Galaxy s6 and Oneplus One. What can be happening? I've checked previous questions here and tried all this:</p>

<ul>
<li>Run configurations: no matter if I chose usb device or show the window, it does not work. </li>
<li><code>Tools &gt; Android &gt; Enable ADB integration</code>: didn't help</li>
<li>Command line <code>adb devices</code> does not detect any either.</li>
<li>I've revoked and granted again USB authorizations. Still not working.</li>
<li>I've tried other apps I have, none work.</li>
<li>Restarted phones</li>
<li>Restarted android studio</li>
<li>Restarted computer</li>
</ul>

<p><em>(Note: if I start an emulator it works, but I'd prefer to use physical device since I have to scan real barcodes)</em> </p>

<p>Thanks a lot in advance.</p>