Have you made upgrades for the titles that MC's Mother and Father have yet? I've almost doubled my stats (around 3k each now) and on a test none of those leveled this time.
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All of the titles related to stats are maxed out once you get to 900. In the next version, there will be hidden scenes and conversations in various locations if you've exceeded that number (the highest required scene is locked behind endurance of 5020+), but in the current version, the only value of additional stats is combat.