You must be logged in to download files-Error is driving me crazy!

My site’s been up for a long time, and this issue JUST started. I sell downloadable ebooks.

The links from the customer’s confirmation email AND the download links from their account page are all directing them to the Dashboard tab with the error message–“You must be logged in to download files” error message.

It’s not anything they’re doing wrong, because it happens to me too, and I’m logged in as administrator. Can someone PLEASE help. I’ve been able to figure out so many issues over the years, but I don’t even know where to start with this one.

I didn’t put my url because the site sells nsfw books and I didn’t want to have to mark the question as mature. And I don’t think there’s a way to recreate this without a purchase anyway.