I normally do my updates with pkcon, first refreshing and then updating. It's always worked well, but twice recently, I've had pkcon update tell me that "No packages require updating to a newer version", only to have Discover tell me that updates are available. I've installed them from Discover, but I'm curious as to why pkcon and discover don't agree about which packages need updates.

Is this a known issue? I'm wondering whether perhaps pkcon and discover aren't using exactly the same repositories.