The default milk capacity for all npcs start with 2000. Thats why its displayed like that. once you interact, the milk capacity will drop to zero when she is not lactating.
Not lactating npc milk capacity is 0. I will fix that to show actual capacity on future updates.
hiring and reloading bug will be fixed. thanks for mentioning it.
can you share the corrupted save file with me? should be located on your C:\Users\<UserName>\AppData\LocalLow\Beetle\HealthPoints