I am not 100% sure but it might be that Tier 3 Factor Boost Autoprestiger doesn't check sluggish milestone while offline. I set up a run for a milestone and it ruined it(i had T3 turned on)...
You can always hit the "Quests" button on the main menu to see where else you can earn free cards and gems. If you have completed the daily quests, campaign, etc, you can still play to earn experience for your commanders, or improve your skill rating and climb the leaderboard! Daily quests of course reset each day and give you a new opportunity to earn gems and cards.
level all items in the set to 100.