I think it’s as you say, you can copy single files/photos, but not folders, unless you remove the card and put it directly into your Mac. Why can’t you just do that - is it stuck?
If I don’t have to remove it, then why do it? That’s the whole point of the card! I like to back up my songs regularly, don’t want to keep taking it in and out every 2 days etc.
Gonna try Downrush next, if it doesn’t work natively.