Sub-Classes not showing up for my players. Master Tier.

I am a DM with a Master Tier subscription, and have a few campaigns open for various games I'm running. I own digital copies on my account for all of the 2024 books, including PHB, DMHB, and MM. 

However, when my players create a new 3rd-level character, they are still only seeing the single free sub-class. For example, my wife created a 3rd-level paladin in my campaign, and only the Oath of Devotion showed up. 

I believe this has happened a few times in the past month as we've begun a new campaign, but I can't be sure. 

Is there something else I need to do? Thanks.

 Thanks! I'll follow through with this. I didn't know about the campaign limit. I had 10 active campaigns, but half of them were for trying things out and for old campaigns.