>>So this past weekend, I went out and shot the .58 cal Ardessa muzzleloader. After the first shot, it was extremely difficult to load and I only fired a few. This led me to determine that I obviously needed to give it a really good cleaning.<<
Is this a new gun, with a new barrel? If so, that barrel needs a good cleaning to remove machining oils, before any range time.
Though it sounds like you have the problem solved, at least for now.