For some owners, the Club Dues are being billed with one of their other VOIs. That was the case for me.
For others, the Club Dues are apparently being billed separately and those bills may not have gone out yet. Reportedly they are due (payable) at the end of January.
If you have an enrolled week and an unenrolled (but mandatory VSN) week, you might owe both Abound Club Dues and VSN Club Dues. I would assume that if this is your situation and you haven't seen either Club Dues show up on a MF invoice, then you'll be separately billed for both of them. Someone else posted recently that MVC is working on those bills.
If your unenrolled week is voluntary, then so far as I know, you wouldn't have to pay VSN Club Dues on it. But I infer from your post that your Vistana week is enrolled in VSN but not Abound. Maybe if you're lucky they'll let you off with just one Club Dues? I don't have any unenrolled weeks so I can't say for sure.