I tried with cutoff set to 0 and it still idles waiting for work from pool at some point.
Lately miner is doing OK for about an hour and then stops receiving work from poll and idles. Sometimes it idles for at most 1-2 minutes, sometimes it idles more than 1h.
Other than making sure that you actually apply the settings I don't know what to say. If you set the profit cutoff to 0 or less it will not shut the miner off. Perhaps you have issues with your internet losing connection or sgminer itself idling your GPUs due to overheating.