"Can I sleep?"
Translation:क्या मैं सो सकता हूँ?
सकना is not exactly a full verb on its own. It is always used with the stem of another verb. You can think of [verb stem]+सकना (eg: सो सकना) as being a sort of compound verb.
This is different from one verb being used as the object of another as in मैं सोना चाहता हूँ।
It might be because you used हूं instead of हूँ. When there are no other diatrics on top of the line, you cannot use the dot in place of the moon-dot.
However, the more likely reason is that the alternate translation has just not been added yet. You can report it if you encounter the sentence again.