→Sneak Suppression: Reveal icon
Subsequently crouching to return to sneak, or using concealing skills such as the Nightblade's Shadow Cloak, will have whatever success in hiding you again that they would in any combat situation: mixed, depending on your circumstances. However, if you can regain sneak, you can immediately attack again and have the usual sneak multipliers apply.
=== Sneak Suppression ===
Sometimes your ability to sneak is suppressed. There are various things that can cause this: