My main file doesn't show recent updates (last one was 7 months ago) and there's no history.

Thanks for posting here, juntjoo. Let’s have a look into this. 

To clarify, you don’t see your old updates on any Dropbox platform, not even on www.dropbox.com, correct? 

Do you remember which Dropbox platform you used, in order to edit this file?

In the meantime, I’d also like you to visit your Events page here; if you further scroll down, do you see any mentions of the last updates you made? 

Finally, I'd like a screenshot of what you see when checking the version history of your file.

Let me know what you find.