I think ebay are tinkering with their site in the background. If you click on print a shipping label you can print a packing slip, but it's nowhere near as detailed as the old invoices. I actually got to call them yesterday to report the issue and the CS rep said they were unaware of any issues! 

I've also noticed that if you use MyPost Business to print your shipping labels, the tracking numbers are not importing into ebay. You have to manually enter them.

My suspicion is ebay are making changes on the quiet and will spring some new horror on us and pass it off as some new feature that's supposed to be of benefit to sellers!!