Mine's dropping leaves right now too. In my case I'm apt to think it's just leaf senescence since I'm guessing each branch is probably on a three-year cycle. HOWEVER! No brown spots. Just yellowing leaves. Underwatering can cause this too, but again, no brown spots. (Or it could be from the really atrocious soil I've got it in. I'll deal with that tomorrow).

They're prone to issues from overwatering. Overwatering, from what I've seen, doesn't cause yellowing so much as sudden and spontaneous branch wilting and dropping. In other words, they drop while green. Also it's not a slow death either.

Replanting also stresses them out, but you mentioned that happening and them getting over it.

I keep my Ming Aralia at home instead of my dorm. My dorm's a far more humid environment. Aralias theoretically need higher humidity, but my house has forced air heating and whenever I'm home for any length of time my hands chap like crazy so the humidity there's got to be very low. Despite some really minor tip burn, the aralia does fine.

So maybe the humidity is too high for it and causing some sort of leaf fungus/rot?

I am not sure its humidity to be honest, I usually mist at night and then allow it to dry throughout the day where it drops to about 40%. Some nights I won't even mist at all, and skip a day to act like a dry spell and help keep fungus/mold from spreading on my substrate.

And throughout the day the temperatures are 74-75 and nights around 72 degrees.

The brown spots are whats concerning me to be honest, and since its not on any of the other plants in the different tanks I have no clue what its being caused by. Not to mention since it switched branches now.