So many items suddenly 'null' or 'no longer available'

I've been working on my reviews and I've noticed today that a whole bunch of them are either 'null' or 'no longer available' and I'm taken to the Dog page. I've had this happen in the past so it's nothing new, but now, among my list of 31 to be reviewed items there are 8. Eight! missing. Some are recent, but others were ordered in late Jan/early Feb and didn't arrive at my home until a week or so. Is anyone else seeing this?