In the Rules Reference the restriction on cloaking and devices says, "Each ship cannot drop or launch a device during the same phase that it decloaked."
Obviously this expressly forbids decloaking, then dropping a device. But does it stop you from dropping a device, then decloaking?
I don't think it does, since that would require the game to look into the future and say, 'since you're planning on decloaking this phase, you can't drop that device first.'