Since Genymotion virtual devices update ver. 2.14.0, we have dropped support for Android versions below 4.4.
Genymotion Desktop 3.0 can still create devices with those Android versions (using Genymotion Virtual Devices 2.13). But they will not be available in Genymotion Desktop 3.1.
If you still have such devices, we recommend migrating your setup to at least Android 4.4.