I was getting SampleRate not supported errors in the AudioEngine when testing VL.Audio in vvvv gamma.
Turns out the issue was that a disconnected BT device was selected in ASIO4ALL. The error however also prevented the Control Panel from being opened from gamma as the AsioOut being fed into the ShowControlPanel node is null when AudioEngine.AsioOut fails as in this case.
In vvvv beta opening the Control Panel works even in this situation. If possible please consider reworking the Control Panel logic so it opens at all times. You can also only notice these errors when RuntimePauseOnError is enabled so it may be nice to report error messages.
In the meantime it is possible to always open the Control Panel from the tray (there is an icon) - had to look that up in the manual :)