Ticket Upgrades

Has anyone been successful upgrading tickets thru the MLB App? I get tickets free from work between sections 140 and 146. 4 nice seats. Up until 2 years ago, I was able to upgrade them to Club Seats for $14 to $18 a ticket. For the past 2 years, I haven't been able to. I see 4 tickets available in Club Seats and the app still says no upgrades available. Can Season Ticket holders put a block on upgrading?